Data transmission method, terminal, and base station in LAA-LTE system

ABSTRACT

The present disclosure relates to example data transmission methods, user equipment, and access network devices in an LAA-LTE system. An example data receiving method includes determining, by user equipment, first information of a first cell. The user equipment determines a first subframe based on the first information, where a downlink data transmission length of the first subframe is less than a first threshold. The user equipment then determines a data transmission characteristic of the cell in the first subframe based on a preset condition, so as to receive, based on the data transmission characteristic, data including the first subframe. In doing so, a data transmission characteristic of a base station or a terminal is standardized, and a reference signal such as a DRS can be correctly identified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/968,964, filed on May 2, 2018, which is a continuation ofInternational Application No. PCT/CN2015/095214, filed on Nov. 20, 2015,which claims priority to International Patent Application No.PCT/CN2015/094066, filed on Nov. 6, 2015. All of the afore-mentionedpatent applications are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to the field of communicationstechnologies, and in particular, to an LTE system working on anunlicensed frequency band.

BACKGROUND

In a wireless communications network, devices need to use a frequencyresource to transmit information. The frequency resource is alsoreferred to as a spectrum or a frequency band. The frequency band mayinclude an authorized frequency band and an unauthorized frequency band.The unauthorized frequency band is also referred to as an unlicensedfrequency band. The authorized frequency band is a dedicated frequencyresource of some operators. The unlicensed frequency band is a commonfrequency resource in the wireless communications network. With thedevelopment of communications technologies, an increasing amount ofinformation is transmitted in the wireless communications network.Transmitting information by using the unlicensed frequency band canimprove a data throughput in the wireless communications network andbetter meet user requirements.

Using an Licensed-Assisted Access Using LTE (LAA-LTE) system as anexample, an LAA-LTE technology is mainly intending to use a CarrierAggregation (CA) configuration and structure in an existing Long TermEvolution (LTE) system, to configure, on the basis of configuring acarrier on a licensed frequency band (briefly referred to as a licensedcarrier in this specification) of an operator for communication,multiple carriers on an unlicensed frequency band (briefly referred toas unlicensed carriers in this specification), and use the unlicensedcarriers for communication with the assistance of the licensed carrier.That is, an LTE device may use a CA manner, to use a licensed carrier asa Primary Component Carrier (PCC) or a primary cell (PCell), and use anunlicensed carrier as an secondary component carrier (SCC) or ansecondary cell (SCell). In this way, the LTE device not only caninherit, by using the licensed carrier, conventional advantages of theLTE device in wireless communication, for example, advantages in suchaspects as mobility, security, quality of service, and simultaneousscheduling processing for multiple users, but also can implement networkcapacity offloading by using the unlicensed carrier, to reduce load ofthe licensed carrier. When using an unlicensed frequency band resource,an LAA system needs to obey specifications formulated by various regionsfor using an unlicensed frequency band.

Description of an Unlicensed Frequency Band:

Resource sharing on an unlicensed frequency band refers to that onlylimitations on indexes such as transmit power and out-of-band leakageare set for use of a particular spectrum, to ensure that a basiccoexistence requirement is met between multiple devices that use thefrequency band, and a radio technology, an operating enterprise, and aservice life are not limited, but quality of service on the frequencyband is not ensured. An operator may implement network capacityoffloading by using an unlicensed frequency band resource, but needs toobey regulations and requirements of different regions and differentspectrums for the unlicensed frequency band resource. These requirementsare generally formulated to protect a common system such as a radar andensure that multiple systems do not impose harmful impact to each otheras far as possible and fairly coexist, and include a transmit powerlimitation, an out-of-band leakage index, and indoor and outdoor uselimitations, and some regions further have some additional coexistencepolicies and the like.

Analysis on a Coexistence Specification of an Unlicensed Frequency Band:

For an unlicensed target frequency band that LAA-LTE considers to use,an listen before talk (LBT) coexistence specification needs to be obeyedin some regions and countries, for example, Europe and Japan. The listenbefore talk LBT is a coexistence policy between systems. When a wirelesscommunications device (for example, for an LTE or LAA-LTE system, thewireless communications device may include a base station and userequipment) occupies the unlicensed frequency band for communication, adetect before use (that is, the LBT) rule needs to be used first. Abasic idea of the LBT is: Before sending a signal on a channel, eachcommunications device needs to first detect whether a current channel isidle, that is, whether it can be detected that a nearby node isoccupying the channel detected by the communications device (that is,the current channel) to send a signal. This detection process may bereferred to as a clear channel assessment (CCA). If it is detectedwithin a period of time that the channel is idle, the communicationsdevice can send a signal. If it is detected that the channel has beenoccupied, the communications device currently cannot send a signal. Inthe foregoing process, the detecting whether a channel is idle may beimplemented through signal detection, energy detection, or the like.Correspondingly, if no particular signal is detected, for example, for aWireless Fidelity (Wi-Fi) system, the particular signal may be apreamble signal Preamble, it may be considered that the channel is idle.If energy detection is used, if received or detected energy is lowerthan a given threshold, it may also be considered that the channel isidle. Referring to FIG. 1, FIG. 1 is a schematic diagram ofopportunistic data transmission on an unlicensed frequency band inLAA-LTE according to the prior art. In FIG. 1, based on thecharacteristic of the LBT, data transmission of an LTE device on theunlicensed frequency band is opportunistic, that is, not continuous.

To effectively use an unlicensed frequency band resource to transmitdata and improve spectrum utilization efficiency, on an unlicensedfrequency band, an LTE system may use a time resource less than onesubframe (a partial subframe) and a frequency resource to transmit data,as shown in FIG. 2. FIG. 2 is a schematic diagram of opportunistic datatransmission in a partial subframe on an unlicensed frequency band inLAA-LTE according to the prior art. In FIG. 2, data transmission in apartial subframe (that is, less than one subframe) in the LAA-LTE on theunlicensed frequency band is opportunistic. A time length of the partialsubframe is generally less than 1 ms, a time length of a completesubframe is generally 1 ms. For example, when time and frequencyresources included in the partial subframe are all used in downlink datatransmission, a time length of the partial subframe that is used in thedownlink data transmission is less than 1 ms.

Because a length of a partial subframe is less than 1 ms, impact iscaused to sending of a reference signal of an LTE system. The referencesignal herein includes a discovery reference signal (DRS), acell-specific reference signal (CRS), a channel state informationreference signal (CSI-RS), and the like. The reference signal may beused for an radio resource management (RRM) measurement, and may also beused for a channel state information (CSI) measurement. Using a DRS asan example, for opportunistic sending of data on an unlicensed frequencyband, to resolve an radio resource management (RRM) measurement problemof user equipment (UE), the discovery reference signal (DRS) is used onthe unlicensed frequency band to support an RRM measurement of theunlicensed frequency band. The RRM measurement herein includes ameasurement for a serving cell and/or a neighboring cell by the UE, forexample, an RSRP (Reference Signal Received Power, reference signalreceived power) measurement, an reference signal received quality (RSRQ)measurement, or an received signal strength indicator (RSSI)measurement. Considering an inter-frequency measurement problem, the DRSis generally sent in a configured discovery signals measurement timingconfiguration (DMTC), and duration of the DMTC is 6 milliseconds. TheDRS includes a primary synchronization signal (PSS), an secondarysynchronization signal (SSS), a CRS, and a configurable CSI-RS. A timerange including DRS sending is generally referred to as a DRS Occasionor DRS occasion duration, and may be represented by an integer quantityof orthogonal frequency division multiplexing (OFDM) symbols, or may berepresented by an integer quantity of subframes. For example, assumingthat the DRS occasion duration is one subframe, a representation form oftime and frequency resources for sending a DRS is shown in FIG. 3. FIG.3 is a schematic diagram of a DRS according to the prior art. As seenfrom reference signals included in the DRS, if the DRS does not includea configurable CSI-RS, the DRS may be less than 1 ms in time, that is,may include only 12 OFDM symbols. Herein, that the DRS includes 12 OFDMsymbols in time is described with respect to a quantity of OFDM symbolsoccupied by a start position to an end position of the DRS. In FIG. 3,within one subframe (1 ms), the start position of the DRS is a firstsymbol (carrying a CRS), and the end position of the DRS is a twelfthsymbol (carrying a CRS). Therefore, the DRS includes 12 OFDM symbols intime. It should be noted that FIG. 3 is considered for a case in which adownlink data transmission configuration is a normal cyclic prefix, andFIG. 3 shows only REs (Resource Element, resource element) occupied by aDRS in time and frequency resources consisting of 12 subcarriers and 14OFDM symbols (corresponding to a length of one subframe in the normalcyclic prefix configuration), where the DRS includes a PSS, an SSS, anda CRS.

Generally, when UE executes an RRM measurement, especially an RRMmeasurement of a neighboring cell (which is not a serving cell of theUE), the UE first determines, on a target frequency band based onwhether a PSS and an SSS are detected, whether a target cell exists onthe target frequency band. Herein, a carrier on which the target cell islocated is the target frequency band. Then the UE may determine whetherthere is a DRS in a DMTC, and if the UE detects a PSS and an SSS in theDMTC, the UE determines that there is a DRS in the DMTC (because a DRSincludes a PSS and an SSS). Then the UE uses a reference signal includedin a DRS occasion (a time range for DRS sending), such as a CRS, or aCRS and a CSI-RS, to execute the RRM measurement. This causes a problem,that is, in a case in which an LAA-LTE system performs opportunisticdata transmission and supports data transmission in a partial subframe,due to transmission in the partial subframe, complete DRS data sendingand receiving cannot be ensured, causing the UE to misinterpret the DRS,which directly causes an incorrect RRM measurement when the UE executesan RRM measurement of a neighboring cell.

Similarly, the partial subframe also affects sending of a CSI-RS.Currently, transmission in a partial subframe also occurs in an LTEsystem. That is, in a time division duplexing (TDD) system, a datatransmission length of a downlink pilot timeslot (DwPTS) included in aspecial subframe is less than 1 ms, and for user equipment in an LTEsystem release 12, CSI-RS transmission is not supported in the DwPTS.Generally, a CSI-RS resource is periodically configured. Foropportunistic transmission on an unlicensed frequency band, if thepartial subframe does not support CSI-RS data transmission, either,sending of a periodic CSI-RS may be missed, and a measurement by theuser equipment on channel state information of the unlicensed frequencyband is affected.

In conclusion, for an LTE system working on an unlicensed frequencyband, in the case of opportunistic data transmission, to improvespectrum utilization efficiency, transmission in a partial subframe maybe used. When the transmission in a partial subframe is used, how to seta data transmission feature of the partial subframe to ensure that userequipment correctly interprets a reference signal in the partialsubframe and ensure an accurate RRM and/or CSI measurement is animportant problem to be resolved.

SUMMARY

The present invention provides a data transmission method, userequipment, and an access network device in an LAA-LTE system, to resolvea DRS misinterpreting problem.

According to a first aspect, the present invention provides a datareceiving method. First, user equipment determines first information ofa first cell. Then the user equipment determines a first subframe basedon the first information, where a downlink data transmission length ofthe first subframe is less than a first threshold. Finally, the userequipment determines a data transmission characteristic of the cell inthe first subframe based on a preset condition.

According to a second aspect, the present invention provides a datasending method. First, an access network device determines a downlinkdata transmission length of a first subframe transmitted by a firstcell. The downlink data transmission length of the first subframe isless than a first threshold. Then the access network device determines adata transmission feature of the first cell in the first subframe basedon a preset condition.

According to a third aspect, the present invention provides userequipment. The user equipment includes a processor. The processor isconfigured to: determine first information of a first cell, anddetermine a first subframe based on the first information. A downlinkdata transmission length of the first subframe is less than a firstthreshold. The processor is further configured to determine a datatransmission characteristic of the first cell in the first subframebased on a preset condition.

According to a fourth aspect, the present invention provides an accessnetwork device. The access network device includes a determining unit.The determining unit is configured to determine a downlink datatransmission length of a first subframe transmitted by a first cell,where the downlink data transmission length of the first subframe isless than a first threshold. The determining unit is further configuredto determine a data transmission feature of the first cell in the firstsubframe based on a preset condition.

According to the data transmission method, the user equipment, and theaccess network device provided in the present invention, a prior-artproblem is resolved that, in a case in which an LTE system performsopportunistic data transmission and supports data transmission in apartial subframe, due to transmission in the partial subframe, completeDRS data sending and receiving cannot be ensured, causing UE tomisinterpret a DRS. According to the data transmission method in thepresent invention, a DRS can be correctly interpreted, implementing acorrect RRM and/or CSI measurement.

In an optional implementation manner, the first information is controlinformation and/or a reference signal including a reference sequenceand/or pre-configuration information, where the control informationand/or the reference signal including a reference sequence is used toindicate that the downlink data transmission length of the firstsubframe is less than the first threshold, and the configurationinformation is used to indicate a longest time within which the firstcell transmits data on a carrier on which the first cell is located.

In an optional implementation manner, the preset condition is that thefirst subframe is a first subframe or a sixth subframe in a radio frame,and the first subframe is located in a DMTC of the carrier on which thefirst cell is located; and the data transmission characteristic is thata last OFDM symbol of a first slot included in the first subframe doesnot include a primary synchronization signal and/or a second last OFDMsymbol of a first slot included in the first subframe does not include asecondary synchronization signal.

In an optional implementation manner, the preset condition is that thefirst subframe is a first subframe or a sixth subframe in a radio frame,and the first subframe is located in a DMTC of the carrier on which thefirst cell is located; and the data transmission characteristic is thatthe downlink data transmission length of the first subframe is anelement included in a first time set.

In an optional implementation manner, when a downlink data transmissionconfiguration of the first cell is a normal cyclic prefix, the elementincluded in the first time set is only: one or more of three OFDMsymbols, six OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13 OFDMsymbols; or when a downlink data transmission configuration of the firstcell is an extended cyclic prefix, the element included in the firsttime set is only: one or more of three OFDM symbols, five OFDM symbols,10 OFDM symbols, or 12 OFDM symbols.

In an optional implementation manner, if the preset condition is thatthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is located in a DMTC of the carrier onwhich the first cell is located, the data transmission characteristic isthat the downlink data transmission length of the first subframe is anelement included in a second time set. If the preset condition is thatthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is not located in a DMTC of the carrier onwhich the first cell is located, the data transmission characteristic isthat the downlink data transmission length of the first subframe is anelement included in a third time set. The second time set has an elementdifferent from that in the third time set.

In an optional implementation manner, when a downlink data transmissionconfiguration of the first cell is a normal cyclic prefix, the elementincluded in the second time set is: one or more of three OFDM symbols,six OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols,and the element included in the third time set is: one or more of threeOFDM symbols, six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols. Whena downlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the second time set is:one or more of three OFDM symbols, five OFDM symbols, 10 OFDM symbols,or 12 OFDM symbols, and the element included in the third time set is:one or more of three OFDM symbols, five OFDM symbols, eight OFDMsymbols, nine OFDM symbols, 10 OFDM symbols, or 12 OFDM symbols.

In an optional implementation manner, a data transmission start positionof the first subframe is on a subframe boundary, and the first subframeis a last subframe in a transmission burst.

In an optional implementation manner, the carrier on which the firstcell is located belongs to an unlicensed frequency band.

In an optional implementation manner, the determining, by the userequipment, a data transmission characteristic of the first cell in thefirst subframe based on a preset condition includes: When a timeresource of a CSI-RS and/or a CSI-IM of the user equipment overlaps thefirst subframe, the first subframe includes the CSI-RS and/or the CSI-IMof the user equipment. In an optional implementation manner, thedetermining, by the access network device, a data transmissioncharacteristic of the first cell in the first subframe based on a presetcondition includes: when the first subframe includes a CSI-RS and/or aCSI-IM, sending the first subframe including the CSI-RS and/or theCSI-IM.

For user equipment in an LTE system release 12, CSI-RS transmission isnot supported in a DwPTS, but in the embodiments, CSI-RS transmissioncan be supported, so that channel state information of an unlicensedfrequency band can be measured.

In an optional implementation manner, the reference sequence is one ormore of a constant amplitude zero auto correlation sequence, a binarysequence, an m sequence, a pseudo-random sequence, or a ZC sequence.

In an optional implementation manner, when a downlink data transmissionconfiguration is a normal cyclic prefix, the downlink data transmissionlength of the first subframe is less than 12 OFDM symbols. Further, thedownlink data transmission length of the first subframe is less than 12OFDM symbols but greater than five OFDM symbols. When a downlink datatransmission configuration is an extended cyclic prefix, the downlinkdata transmission length of the first subframe is less than 10 OFDMsymbols. Further, the downlink data length of the first subframe is lessthan 10 OFDM symbols but greater than four OFDM symbols.

In an optional implementation manner, the user equipment is a relay or aterminal device, and the access network device is an LTE base station.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of opportunistic data transmission on anunlicensed frequency band in existing LAA-LTE;

FIG. 2 is a schematic diagram of opportunistic data transmission in apartial subframe on an unlicensed frequency band in existing LAA-LTE;

FIG. 3 is a schematic diagram of an existing DRS;

FIG. 4 is a schematic diagram of data transmission between an accessnetwork device and user equipment according to an embodiment of thepresent invention;

FIG. 5 is a flowchart of a data receiving method according to anembodiment of the present invention;

FIG. 6 is a schematic diagram of a data transmission burst according toan embodiment of the present invention;

FIG. 7 is a schematic diagram of a time range, corresponding to oneburst data transmission of a first cell, of a second cell according toan embodiment of the present invention;

FIG. 8 is a schematic diagram of determining a first subframe accordingto pre-configuration information according to an embodiment of thepresent invention;

FIG. 9 is a schematic structural diagram of a TDD LTE system frame;

FIG. 10 is a schematic diagram of a DMTC according to an embodiment ofthe present invention;

FIG. 11 is a flowchart of a data sending method according to anembodiment of the present invention;

FIG. 12 is a schematic diagram of user equipment according to anembodiment of the present invention; and

FIG. 13 is a schematic diagram of an access network device according toan embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The following describes the embodiments of the present invention withreference to accompanying drawings.

FIG. 4 is a schematic diagram of data transmission between an accessnetwork device and user equipment. FIG. 4 is a simple schematic diagramof a wireless communications system, and does not limit an applicationscenario of the present invention. For example, a wirelesscommunications system in the present invention may be an LTE systemindependently working on an unlicensed frequency band, or may be alicensed-assisted access using LTE system, that is, an LAA-LTE system.

In FIG. 4, an access network device and user equipment communicate witheach other. In an example, the access network device is a base station.The base station may be a base station corresponding to a cell, such asa macro base station, or may be a base station corresponding to a smallcell. Only a macro base station is used as an example in FIG. 4 to showdata transmission between an access network device and user equipment.Actually, the access network device in the present invention may be anytype of base station. The small cell herein includes: a metro cell, amicro cell, a pico cell, a femto cell, and the like. These small cellsare characterized by small coverage and low transmit power, and areapplicable to providing a high rate data transmission service. In anexample, the user equipment (UE) may be a terminal device, such as amobile phone terminal, or may be a relay. Any device that can performdata communication with the access network device (for example, a basestation) may be the user equipment.

In FIG. 4, a first cell and a second cell are neighboring cells. Theremay be multiple neighboring cells, and only two cells are used as anexample in FIG. 4 for description. In FIG. 4, a first access networkdevice (for example, an LTE base station) serves two cells, that is, thefirst cell and the second cell. The first cell and the second cell maybe cells jointly used through CA. For an LAA-LTE system, the first cellmay be a cell on an unlicensed frequency band, that is, may beconsidered as a secondary cell, and the second cell may be a cell on alicensed frequency band, that is, may be considered as a primary cell.The first cell and the second cell may jointly provide a data service tofirst user equipment through CA. Similarly, in FIG. 4, a second accessnetwork device (for example, an LTE base station) serves two cells, thatis, a third cell and a fourth cell. The third cell and the fourth cellmay be cells jointly used through CA. For an LAA-LTE system, the thirdcell may be a cell on an unlicensed frequency band, that is, may beconsidered as a secondary cell, and the fourth cell may be a cell on alicensed frequency band, that is, may be considered as a primary cell.The third cell and the fourth cell may jointly provide a data service tosecond user equipment through CA. It should be noted that the accessnetwork devices may serve multiple cells, and carriers on which thesecond cell and the fourth cell are located are not limited. In FIG. 4,the first cell and the second cell are in a co-site deployment, and bothbelong to the first access network device, and the third cell and thefourth cell are in a co-site deployment, and both belong to the secondaccess network device. It should be noted that, in the embodiments ofthe present invention, multiple cells that are aggregated through CA maybe not in a co-site deployment. In addition, in this embodiment of thepresent invention, besides using a CA manner to enable multiple cells toprovide a data service to user equipment, a non-CA manner such as a dualconnectivity (DC) manner may be used to enable multiple cells to providea data service to user equipment.

It should be noted that, in the embodiments, a licensed frequency bandand an unlicensed frequency band both may include one or more carriers,and carrier aggregation or dual connectivity is performed on thelicensed frequency band and the unlicensed frequency band.

Besides, multiple cells may simultaneously work on one carrier at a samefrequency. In some special scenarios, it may be considered that in anLTE system, a concept of a carrier is equivalent to that of a cell. Forexample, in a CA scenario, when a secondary carrier is configured forUE, both a carrier index of the secondary carrier and a cellidentification (Cell ID) of a secondary cell working on the secondarycarrier are carried. In this case, it may be considered that a conceptof a carrier is equivalent to that of a cell. For example, that UEaccesses a carrier is equivalent to that the UE accesses a cell. In theembodiments of the present invention, the concept of a cell is used fordescription.

In an LTE system, to enable user equipment to effectively access asystem, an LTE base station (or a cell served by an LTE base station,for example, a first/second/third/fourth cell in FIG. 4) generally sendsa synchronization signal and public broadcast information at a fixedtime position and a fixed frequency position. For frequency divisionduplexing (FDD), a PSS and an SSS are usually sent in a subframe 0(that, a first subframe) and a subframe 5 (that is, a sixth subframe) ineach radio frame. The subframe 0 represents a subframe whose subframeindex number is 0, and the subframe 5 represents a subframe whosesubframe index number is 5.

A typical scenario is: A first access network device (which, in theembodiments of the present invention, may be an LTE base station in FIG.4, or may be a cell served by the LTE base station, for example, thefirst cell) sends a PSS and an SSS in a subframe 0 or a subframe 5 in aradio frame, where a subframe including the PSS and the SSS is a partialsubframe, and the subframe including the PSS and the SSS is located in aDMTC of a carrier on which the first cell is located. Signals, namely,the PSS and the SSS, included in the subframe 0 or the subframe 5 arethe same as signals, namely, a PSS and an SSS, in a DRS. Therefore, inthis case, when user equipment (the first user equipment or the seconduser equipment) obtains a DRS in the first cell, because a subframereceived by the user equipment includes the PSS and the SSS, the userequipment (the first user equipment or the second user equipment)incorrectly determines that the subframe includes a complete DRS.However, actually, the subframe is a partial subframe, and DRSinformation included in the partial subframe is not complete. As aresult, the user equipment (the first user equipment or the second userequipment) misinterprets the DRS. If the user equipment (the first userequipment or the second user equipment) uses the misinterpreted DRS toperform an RRM measurement or channel state information measurement orstate information interference measurement, an incorrect measurementresult is obtained.

FIG. 5 is a flowchart of a data receiving method according to anembodiment of the present invention.

S501: User equipment determines first information of a first cell.

In an example, the user equipment detects the first information in thefirst cell. Further, the user equipment detects the first information ona working carrier or carrier frequency of the first cell, where theworking carrier of the first cell belongs to an unlicensed frequencyband. That is, the user equipment detects the first information on atarget carrier, where the target frequency band is a frequency band onwhich the first cell is located. That the target frequency band is afrequency band on which the first cell is located refers to that thefirst cell may transmit data by using the target frequency band.

For example, if the working carrier frequency of the first cell is F1,the user equipment detects the first information on a frequency resourcecorresponding to the working carrier frequency F1. The frequencyresource may be represented by a center frequency of the frequencyresource and a size of the frequency resource. The working carrier ofthe first cell (which may also be referred to as a carrier on which thefirst cell is located) may be configured by an access network device(for example, a base station) in the first cell for the user terminal.After the user terminal obtains the configured working carrier of thefirst cell, the user equipment detects the first information on thecarrier.

Preferably, the first information carries identity information of thefirst cell. For example, the first information carries a cellidentification (Cell ID) of the first cell, so that the user equipmentcan determine whether the first information detected by the userequipment belongs to the first cell.

It should be noted that the first cell may include a serving cell of theuser equipment, and may further include a neighboring cell of theserving cell of the user equipment (for example, the third cell in FIG.4). The serving cell and the neighboring cell may be located on a samecarrier or different carriers.

In an embodiment of the present invention, the first information iscontrol information, and the user equipment detects the controlinformation on a control data channel and/or a service data channel ofthe first cell, or the user equipment detects the control information ona control data channel and/or a service data channel of a second cell,where the first cell is a serving cell of the user equipment, forexample, a secondary cell, and the second cell is also a serving cell ofthe user equipment, for example, a primary cell. A carrier on which thesecond cell is located is different from the carrier on which the firstcell is located. The first cell and the second cell may jointly providea data service to the user equipment through CA or DC. Correspondingly,if the user equipment detects the control information by using thecontrol data channel and/or the service data channel of the second cell,to determine a first subframe, and the first subframe is a subframe inthe first cell, it may be considered that the second cell indicates thefirst subframe by using a cross-carrier indication. If the userequipment detects the control information by using the control datachannel and/or the service data channel of the first cell, to determinethe first subframe, it may be considered that the first cell indicatesthe first subframe by using an intra-carrier indication.

The control data channel of the first cell (or the second cell) is oneor more of control data channels supported by an LTE system, such as aphysical downlink control channel (PDCCH), a physical control formatindicator channel (PCFICH), a physical hybrid automatic repeat requestindicator channel (PHICH), an enhanced physical downlink control channel(EPDCCH), and a physical broadcast channel (PBCH).

The service data channel of the first cell (or the second cell) is oneor more of service data channels supported by the LTE system, such as aphysical downlink shared channel (PDSCH) and a physical multicastchannel (PMCH).

In an example, a subframe that carries the control information is anysubframe that is included in the first cell and that is in one burstdata transmission, referring to FIG. 6; or may be any subframe in thesecond cell. More specifically, the burst data transmission may be anysubframe within a time range, corresponding to one burst datatransmission of the first cell, of the second cell. The second cell andthe first cell are jointly used through CA or DC. Preferably, thecarrier on which the second cell is located and a working frequencyrange of the second cell belong to a frequency resource included in alicensed frequency band. For the working frequency range of the secondcell and the time range, corresponding to the burst data transmission ofthe first cell, of the second cell, refer to FIG. 7. That is, thecontrol information may be sent by using the first cell, or may be sentby using the second cell. That is, the control information may becarried by using time and frequency resources included in the servicedata channel of the first cell or time and frequency resources includedin the control data channel of the first cell, or may be carried byusing time and frequency resources included in the service data channelof the second cell or time and frequency resources included in thecontrol data channel of the second cell. The control information may beuser equipment (UE) specific control information, or may be cellspecific control information. Particularly, when the control informationis UE specific control information, the control information may becarried in downlink data scheduling signaling for scheduling the UE.

FIG. 6 is a schematic diagram of a data transmission burst. In LAA-LTE,data transmission is opportunistic. One time of continuous datatransmission is one burst data transmission, the burst data transmissionincludes multiple subframes, and the multiple subframes include acomplete subframe and a partial subframe. The control information may becarried in any subframe in the burst data transmission. The burst datatransmission herein refers to a time range within which the first cellcan transmit data without using a contention based mechanism such as anLBT mechanism after the first cell preempts an unlicensed frequency bandresource. It should be noted that, in this embodiment of the presentinvention, that the control information is carried in a subframe refersto that the control information is sent by using time and frequencyresources included in the subframe.

FIG. 7 is a schematic diagram of a time range, corresponding to oneburst data transmission of a first cell, of a second cell according toan embodiment of the present invention. More generally, the firstinformation may be carried in another subframe of the second cell, andthe another subframe may indicate a status of one or more subframes inone burst data transmission of the first cell.

It should be noted that, in this embodiment of the present invention,the control information indicates that downlink data transmission of thefirst subframe is less than a first threshold. When the first thresholdis 1 ms, the control information directly indicates that a targetsubframe is the first subframe (for example, a partial subframe).Alternatively, the control information may directly indicate a datatransmission length of a target subframe, and in this case, the UEdetermines, based on a correspondence between the data transmissionlength of the target subframe and the first threshold, whether thetarget subframe is the first subframe (or the partial subframe). Thetarget subframe herein may be any subframe in one burst datatransmission of the first cell, for example, any one of afirst/second/third/fourth/fifth subframe in FIG. 6. Alternatively, thetarget subframe may be any subframe on the carrier on which the firstcell is located. When the first threshold is greater than 1 ms, thecontrol information may indicate whether the target subframe is asubframe in one burst data transmission of the first cell. Explanationof one burst data transmission is the same as above, and details are notdescribed.

In another embodiment of the present invention, the first information isa reference signal including a reference sequence.

Specifically, the user equipment detects, in each subframe included inone burst data transmission of the first cell, whether there is areference signal including a reference sequence, where the first cellmay include a serving cell of the user equipment. Besides, the userequipment may detect, in each subframe included in a second cell,whether there is a reference signal including a reference sequence, todetermine whether a subframe, corresponding to the subframe, of thefirst cell is a first subframe. Herein, the subframe, corresponding tothe subframe, of the first cell may include a subframe having a samesubframe index number as the subframe, or a subframe having a fixedsubframe offset.

Preferably, the user equipment performs detection on a third OFDM symbolin each subframe in one burst data transmission of the first cell, todetect whether there is a reference signal including a referencesequence in the third OFDM symbol. Further, the user terminal detects,in a third OFDM symbol in each subframe included in one burst datatransmission, whether there is a primary synchronization signal (PSS).That is, if the user equipment detects a PSS in a third OFDM symbol in atarget subframe, the user equipment may determine that the targetsubframe is the first subframe (or a partial subframe). Otherwise, theuser equipment may determine that the target subframe is a completesubframe. The target subframe herein is any subframe in one burst datatransmission. Besides, because a CRS carries the identity information ofthe first cell, the user equipment may determine, by detecting the CRS,whether the target subframe is the first subframe. That is, afterdetecting the CRS, the user equipment may determine that a subframeincluding the CRS is the first subframe. In other words, if the CRS isdetected, it indicates that the first cell has preempted an unlicensedfrequency band resource including the carrier on which the first cell islocated, and in this case, a first threshold may be greater than 1 ms.

In this embodiment of the present invention, for a method foridentifying, by the user equipment, one burst data transmission of thefirst cell on the carrier on which the first cell is located, a controlinformation detection method or a reference signal detection method maybe used. This is not limited herein. After determining one burst datatransmission, the user equipment may determine the target subframe.

The reference sequence may include but is not limited to the followingsequences: a constant amplitude zero auto correlation (CAZAC) sequence,a binary sequence, an m sequence, a pseudo-random sequence, and aZadoff-Chu (ZC) sequence.

It should be noted that the reference sequence may correspond todifferent data transmission lengths of the target subframe, whereexplanation of the target subframe is the same as above. In thisembodiment of the present invention, the target subframe may include onesubframe in one burst data transmission of the first cell on the carrieron which the first cell is located, or may be any subframe on thecarrier on which the first cell is located.

In still another embodiment of the present invention, the firstinformation is pre-configuration information, and the pre-configurationinformation indicates a longest time within which the first celltransmits data on the carrier on which the first cell is located. Thelongest data transmission time refers to a maximum time range of oneburst data transmission of the first cell on the carrier on which thefirst cell is located. For example, in Japan, for use of an unlicensedfrequency band, it is clearly defined in a regulation that a maximumdata transmission time is 4 ms. In addition, in Europe, for use of anunlicensed frequency band, it is clearly defined in a regulation that amaximum data transmission time is 10 ms or 13 ms or 8 ms. These valuesmay be understood as a maximum time range of one burst datatransmission. FIG. 8 is a schematic diagram of determining a firstsubframe based on pre-configuration information according to anembodiment of the present invention. In FIG. 8, the user equipment mayfirst determine a start position of one burst data transmission, whichmay be implemented by detecting control information, detecting areference sequence, or the like, which is not specifically limited inthis embodiment of the present invention. In FIG. 8, the user equipmentdetects a CRS and determines a start position of one burst datatransmission, and then obtains a position of a first subframe throughcalculation based on the pre-configuration information. For example, ifa first threshold is a value greater than 1 ms, the first subframe maybe a normal subframe included in the burst data transmission. If thefirst threshold is equal to 1 ms, the first subframe may be a lastsubframe in the burst data transmission, that is, a fifth subframemarked in FIG. 8.

Besides, the pre-configuration information may be a standard protocolspecification, or may be configured for the user terminal by the accessnetwork device in the first cell (for example, an LTE base station) byusing higher layer signaling, for example, indicated to the userterminal by using radio resource control (RRC) signaling.

S502: The user equipment determines a first subframe based on the firstinformation, where a downlink data transmission length of the firstsubframe is less than a first threshold.

In an example, when a downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the first threshold is 14 OFDMsymbols or 1 ms (millisecond); and in this case, a complete subframeincludes 14 OFDM symbols, or a time resource occupied by a completesubframe is 1 millisecond (1 ms). When a downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, the firstthreshold is 12 OFDM symbols or 1 ms; and in this case, a completesubframe includes 12 OFDM symbols, or a time resource occupied by acomplete subframe is 1 millisecond (1 ms).

It should be noted that the first threshold may be greater than 1 ms;and in this case, the first subframe may include a complete subframe, ormay include a partial subframe (that is, a subframe whose length indownlink data transmission is less than 1 ms).

In an embodiment of the present invention, the user equipment determinesthe first subframe based on the control information, and the controlinformation indicates that the downlink data transmission length of thefirst subframe is less than the first threshold. In other words, theuser equipment determines the partial subframe based on the controlinformation, which includes determining a time position of the partialsubframe.

Besides, the control information may indicate that a particular subframeis the first subframe (or the partial subframe), where the particularsubframe may be a subframe carrying the control information, or may be asubframe indicated by the control information. The subframe indicated bythe control information, that is, the particular subframe, may berepresented by a subframe index number, or may be represented by asubframe after the subframe including the control information, where agiven time interval exists between the subframe and the subframeincluding the control information, and the time interval may berepresented by an integer quantity of OFDM symbols or an integerquantity of slots or an integer quantity of Tss. A Ts corresponds to areciprocal of a sampling rate used for data transmission in an LTEsystem. For example, in the LTE system, a length corresponding to 307200Tss is one radio frame, that is, 10 ms, and a length corresponding to15360 Tss is half a subframe (one slot), that is, 0.5 ms.

In FIG. 6, the first subframe is a last subframe in one burst datatransmission (the fifth subframe in FIG. 6) when the first celltransmits data on the working carrier of the first cell (that is, thecarrier on which the first cell is located). The control information maybe carried in the last subframe, to indicate that a current subframe isthe first subframe, or the control information may be carried in anysubframe in one burst data transmission, for example, a second subframe,a third subframe, or a fourth subframe included in the burst datatransmission, to indicate that a last subframe is the first subframe. Itshould be noted that, in FIG. 6, a data transmission length of a firstsubframe included in the burst data transmission is less than 1 ms.Although the first subframe is a partial subframe, the first subframe isnot the first subframe determined based on the first information. Inthis embodiment of the present invention, the first subframe is the lastsubframe in the burst data transmission in FIG. 6, that is, the fifthsubframe in FIG. 6. As can be seen from that a data transmission startposition included in the first subframe is on a subframe boundary. Adata transmission start position included in the first subframe is noton a subframe boundary. Therefore, the first subframe in FIG. 6 is notthe first subframe.

Besides, the subframe carrying the control information may be anysubframe in one burst data transmission of the first cell, or may be anysubframe in the second cell. The second cell is the same as thatdescribed above, and the second cell and the first cell may jointlyprovide a data service to the user equipment through CA or DC or thelike.

In still another embodiment of the present invention, the user equipmentdetermines the first subframe based on the pre-configurationinformation, and the pre-configuration information indicates the longesttime within which the first cell transmits data on the carrier on whichthe first cell is located. The first subframe is a last subframe in thedata transmission, and the user equipment determines the first subframebased on the pre-configuration information.

Preferably, the user terminal obtains a position of the first subframebased on the pre-configuration information by determining a startposition of a data transmission burst. Specifically, the user equipmentdetermines, through blind CRS detection in each subframe included in thefirst cell, whether the first cell has preempted an unlicensed frequencyband resource in the currently detected subframe. Once the user terminaldetects a CRS, the user terminal determines that the first cell haspreempted an unlicensed frequency band resource in the currentlydetected subframe. In this case, the user terminal uses a position ofthe currently detected CRS as a start position of a data transmissionburst, and then determines, based on the pre-configuration information(that is, a configured longest data transmission time), a position of alast subframe included in the burst data transmission, to determine thefirst subframe.

S503: The user equipment determines a data transmission characteristicof the first subframe in the first cell based on a preset condition, sothat the user equipment receives, based on the data transmissioncharacteristic, data including the first subframe.

In an embodiment of the present invention, if the preset condition isthat the first subframe is a first subframe (that is, a subframe 0) or asixth subframe (that is, a subframe 5) in a radio frame, and the firstsubframe is located in a discovery signals measurement timingconfiguration (DMTC) of the carrier on which the first cell is located,the data transmission characteristic is that a last OFDM symbol of afirst slot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. That is, a preset rule (or the determining, bythe user equipment, a data transmission characteristic of the cell inthe first subframe based on a preset condition) is: When the firstsubframe is a first subframe or a sixth subframe in a radio frame, andthe first subframe is located in the DMTC of the carrier on which thefirst cell is located, a last OFDM symbol of a first slot included inthe first subframe does not include a primary synchronization signaland/or a second last OFDM symbol of a first slot included in the firstsubframe does not include a secondary synchronization signal. It shouldbe noted that the preset rule may be explained as “the determining, bythe user equipment, a data transmission characteristic of the cell inthe first subframe based on a preset condition”, which is alsoapplicable to another implementation manner on a user equipment side.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe (that is, a subframe 0)or a sixth subframe (that is, a subframe 5) in a radio frame, the datatransmission characteristic is that a last OFDM symbol of a first slotincluded in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. That is, a preset rule is: When the firstsubframe is a first subframe or a sixth subframe in a radio frame, alast OFDM symbol of a first slot included in the first subframe does notinclude a primary synchronization signal and/or a second last OFDMsymbol of a first slot included in the first subframe does not include asecondary synchronization signal.

In this implementation manner, if the first subframe does not include aPSS and/or an SSS, the user equipment detects no PSS and/or SSS whenexecuting an RRM measurement, and therefore does not incorrectlyconsider that the first subframe includes DRS sending. In this case,even though the first subframe is a partial subframe, the user equipmentdoes not misinterpret the RRM measurement, thereby ensuring accuracy ofthe RRM measurement.

The following describes in detail relationships between a radio frame, asubframe, a slot, and an OFDM symbol. For an LTE system, one radio frameincludes 10 subframes, and each subframe includes two slots. If a datatransmission configuration is a normal cyclic prefix and a subcarrierspacing is 15 KHz, each subframe includes 14 OFDM symbols, and each slotincludes seven OFDM symbols. If a data transmission configuration is anextended cyclic prefix and a subcarrier spacing is 15 KHz, each subframeincludes 12 OFDM symbols, and each slot includes six OFDM symbols. In anLTE system, a radio frame may be represented by a radio frame indexnumber, and the radio frame index number is any integer value in 0 to1023. A subframe may be represented by a position in a radio frame, andthe position in a radio frame may be represented by a subframe index.The subframe index is any integer value in 0 to 9. A subframe whosesubframe index number is M corresponds to an (M+1)^(th) subframe in aradio frame. A slot may also be represented by a position in a radioframe, and the position in a radio frame may be represented by a slotindex. The slot index is any integer value in 0 to 19. A slot whose slotindex number is N corresponds to an (N+1)^(th) slot in a radio frame. AnOFDM symbol may be represented by a position in a subframe, or may berepresented by a position in a slot. The position in a subframe may berepresented by an OFDM symbol index, the OFDM symbol index is an anyinteger value in 0 to 13 or 0 to 11, and an OFDM symbol whose OFDMsymbol index is K corresponds to a (K+1)^(th) OFDM symbol in a subframe.The position in a slot may also be represented by an OFDM symbol index,the OFDM symbol index is any integer value in 0 to 6 or 0 to 5, and anOFDM symbol whose OFDM symbol index is L corresponds to an (L+1)^(th)OFDM symbol in a slot.

As can be seen from that, if the downlink data transmissionconfiguration is a normal cyclic prefix, the last OFDM symbol of thefirst slot refers to a seventh OFDM symbol of the first slot, which isalso a seventh OFDM symbol included in the first subframe, and thesecond last OFDM symbol of the first slot refers to a sixth OFDM symbolof the first slot, which is also a sixth OFDM symbol included in thefirst subframe. If the downlink data transmission configuration is anextended cyclic prefix, the last OFDM symbol of the first slot refers toa sixth OFDM symbol of the first slot, which is also a sixth OFDM symbolincluded in the first subframe, and the second last OFDM symbol of thefirst slot refers to a fifth OFDM symbol of the first slot, which isalso a fifth OFDM symbol included in the first subframe. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

Besides, when the first subframe is a partial subframe, to reducecomplexity, for data transmission of the first subframe, reference maybe made to a data resource mapping manner supported by a downlink pilottimeslot (DwPTS). The DwPTS is a structure in time division duplexing(TDD) and LTE systems, and the DwPTS is included in a special subframe.A frame structure in an existing TDD LTE system includes a downlinksubframe, a special subframe, and an uplink subframe. An example inwhich a radio frame includes two special subframes is used fordescription below, as shown in FIG. 9.

FIG. 9 is a schematic diagram of a frame structure in a TDD LTE system.A length of a special subframe is 1 ms, that is, one subframe, and thespecial subframe consists of a DwPTS, a guard period (GP), and an uplinkpilot timeslot (UpPTS). Currently, the TDD LTE system respectivelydefines different special subframe configurations for two cases: adownlink normal cyclic prefix and a downlink extended cyclic prefix.Different special subframe configurations are different in a length ofat least one of a DwPTS, a GP, or an UpPTS included therein, as shown inTable 1. In Table 1, lengths of the DwPTS and the UpPTS are representedby quantities of symbols, and a time occupied by the GP may becalculated by subtracting a time occupied by the DwPTS and the UpPTSfrom a length of a subframe (that is, 1 ms).

It should be noted that a quantity of OFDM symbols included in the UpPTSin Table 1 is not only applicable to a case in which an uplink is anormal cyclic prefix (NCP), but also applicable to a case in which theuplink is an extended cyclic prefix (ECP). For example, assuming that aspecial subframe configuration is 0, in a case in which the downlink isan NCP, a DwPTS includes three OFDM symbols, and in the cases of theuplink NCP and the uplink ECP, an UpPTS includes one OFDM symbol.

TABLE 1 Normal CP (NCP) Extended CP (ECP) Configuration DwPTS UpPTSDwPTS UpPTS 0 3 1 3 1 1 9 1 8 1 2 10 1 9 1 3 11 1 10 1 4 12 1 3 2 5 3 28 2 6 9 2 9 2 7 10 2 5 2 8 11 2 9 6 2

With reference to a quantity of OFDM symbols supported by the DwPTS,when the downlink data transmission configuration is a normal cyclicprefix, the downlink data transmission length of the first subframe isless than 12 OFDM symbols. Further, the downlink data transmissionlength of the first subframe is less than 12 OFDM symbols but greaterthan five OFDM symbols. When the downlink data transmissionconfiguration is an extended cyclic prefix, the downlink datatransmission length of the first subframe is less than 10 OFDM symbols,or the downlink data length of the first subframe is less than 10 OFDMsymbols but greater than four OFDM symbols.

Besides, considering that when the downlink data transmissionconfiguration is a normal cyclic prefix, a DRS includes 12 OFDM symbolsin time, if a data transmission length of the first subframe is lessthan 12 OFDM symbols, the length is not sufficient to support DRSsending. Therefore, the preset rule may be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols, a last OFDM symbol of a firstslot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Moreover, considering that when the datatransmission length of the first subframe is not greater than five OFDMsymbols, the first cell is limited by the data transmission length andtherefore cannot send a PSS or an SSS in the first subframe, when thedata transmission length of the first subframe is not greater than fiveOFDM symbols, a DRS-based RRM measurement is not affected, either.Therefore, the preset rule may be: When the first subframe is a firstsubframe or a sixth subframe in a radio frame, and the first subframe islocated in the DMTC of the carrier on which the first cell is located,and when the downlink data transmission configuration is a normal cyclicprefix, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols or is less than 12 OFDM symbolsbut greater than five OFDM symbols, a last OFDM symbol of a first slotincluded in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Alternatively, the preset rule may be: When thefirst subframe is a first subframe or a sixth subframe in a radio frame,and the first subframe is located in the DMTC of the carrier on whichthe first cell is located, and when the downlink data transmissionconfiguration is an extended cyclic prefix, when and only when the datatransmission length of the first subframe is less than 10 OFDM symbolsor is less than 10 OFDM symbols but greater than four OFDM symbols, alast OFDM symbol of a first slot included in the first subframe does notinclude a primary synchronization signal and/or a second last OFDMsymbol of a first slot included in the first subframe does not include asecondary synchronization signal.

Besides, the preset rule may be: When the downlink data transmissionconfiguration is a normal cyclic prefix, when the first subframe is afirst subframe or a sixth subframe in a radio frame, when and only whenthe data transmission length of the first subframe is less than 12 OFDMsymbols, a last OFDM symbol of a first slot included in the firstsubframe does not include a primary synchronization signal and/or asecond last OFDM symbol of a first slot included in the first subframedoes not include a secondary synchronization signal. Moreover,considering that when the data transmission length of the first subframeis not greater than five OFDM symbols, the first cell is limited by thedata transmission length and therefore cannot send a PSS or an SSS inthe first subframe, when the data transmission length of the firstsubframe is not greater than five OFDM symbols, a DRS-based RRMmeasurement is not affected, either. Therefore, the preset rule may be:When the first subframe is a first subframe or a sixth subframe in aradio frame, and when the downlink data transmission configuration is anormal cyclic prefix, when and only when the data transmission length ofthe first subframe is less than 12 OFDM symbols or is less than 12 OFDMsymbols but greater than five OFDM symbols, a last OFDM symbol of afirst slot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Alternatively, the preset rule may be: When thefirst subframe is a first subframe or a sixth subframe in a radio frame,and when the downlink data transmission configuration is an extendedcyclic prefix, when and only when the data transmission length of thefirst subframe is less than 10 OFDM symbols or is less than 10 OFDMsymbols but greater than four OFDM symbols, a last OFDM symbol of afirst slot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal.

FIG. 10 is a schematic diagram of a DMTC according to an embodiment ofthe present invention. It should be noted that, in this embodiment ofthe present invention, the DMTC of the carrier on which the first cellis located includes a DMTC configured on the carrier. The DMTC may beunderstood as a DMTC configured for the first cell, or may be understoodas a DMTC configured for a non-first cell. For the user equipment, theDMTC configured on the carrier may correspond to a DMTC of a servingcell of the user equipment, or may correspond to a DMTC of a neighboringcell of the user equipment. The neighboring cell herein refers toanother cell except the serving cell, and the neighboring cell and theserving cell are located on a same carrier. It should be noted that, ifthe DMTC of the carrier on which the first cell is located correspondsto the DMTC of the serving cell of the user equipment, for the userequipment, the user equipment may directly determine a time position ofthe DMTC based on the DMTC configuration of the serving cell, anddetermine the data transmission feature of the first subframe based onthe preset condition. In another aspect, if the DMTC of the carrier onwhich the first cell is located corresponds to the DMTC of theneighboring cell of the user equipment, for the user equipment, the userequipment needs to determine the DMTC of the neighboring cell, and thendetermine the data transmission feature of the first subframe based onthe preset condition. A specific manner of determining, by the userequipment, the DMTC of the neighboring cell includes: indicating, by theserving cell of the user equipment or an access network device to whichthe serving cell belongs, the DMTC of the neighboring cell of the userequipment, or another manner may be used, which is not specificallylimited in this embodiment of the present invention. Correspondingly,the serving cell of the user equipment or the access network device towhich the serving cell belongs needs to first obtain the DMTCconfiguration of the neighboring cell of the user equipment. Throughinteraction, the serving cell and the neighboring cell of the userequipment may obtain the DMTC configuration of each other or obtain theDMTC configuration of one of them. The interaction may be implemented byusing a backhaul link such as X2 or S1 signaling, or may be implementedby using radio signaling, or may be implemented in another manner, whichis not specifically limited in this embodiment of the present invention.Specifically:

Usually, one DMTC is configured for each carrier. Therefore, generally,for the user equipment, regardless of the serving cell of the userequipment or the neighboring cell of the user equipment, as long as theserving cell and the neighboring cell are located on a same carrier,there is only one DMTC corresponding to the user equipment on thecarrier. Using second user equipment in FIG. 4 as an example, for thesecond user equipment, the first cell is a neighboring cell of thesecond user equipment, and the third cell is a serving cell of thesecond user equipment. If the carrier on which the first cell is locatedis the same as a carrier on which the third cell is located, in thisembodiment of the present invention, the DMTC of the carrier on whichthe first cell is located may be understood as the DMTC of the firstcell, and may also be understood as a DMTC of the third cell. The seconduser equipment detects, in the DMTC of the carrier on which the thirdcell is located, whether a DRS exists, and if the DRS exists, maymeasure, by using the detected DRS, a cell including the DRS. Forexample, if the second user equipment detects a DRS of the first cell inthe DMTC of the third cell (which is also the DMTC of the first cell,and is also the DMTC of the carrier on which the first cell is located),the second user equipment may execute an RRM measurement (that is, aneighboring cell measurement) on the first cell by using the detectedDRS. In this case, for the first cell, if a last subframe in a databurst (which may correspond to the first subframe in this embodiment ofthe present invention) is a subframe 0 or a subframe 5, and the subframeis located in the DMTC of the carrier on which the first cell is located(that is, in the DMTC of the third cell), according to the method inthis embodiment of the present invention, not sending a PSS and/or anSSS and limiting the downlink data transmission length of the firstsubframe both can ensure that the second user equipment executes anaccurate RRM measurement on the first cell. For user equipment served bythe first cell, because the DMTC of the first cell may be learned, acorrect assumption may be made on the data transmission feature of thefirst subframe based on the preset rule.

In another case, the DMTC of the first cell is different from the DMTCof the third cell. In this case, the DMTC of the carrier on which thefirst cell is located may be understood as the DMTC of the third cell.In this case, to ensure that user equipment served by the third cell canimplement a correct RRM measurement on the first cell, a datatransmission feature of the first cell in a subframe 0 and/or a subframe5 may be limited, that is, if the subframe 0 and/or the subframe 5 is apartial subframe, regardless of whether the subframe is located in theDMTC of the carrier on which the first cell is located, the first celldoes not send a PSS and/or an SSS in the partial subframe. Further, if adownlink configuration is a normal cyclic prefix, when a downlink datatransmission length of the partial subframe is less than 12 OFDM symbolsor is less than 12 OFDM symbols but greater than five OFDM symbols, thefirst cell does not send a PSS and/or an SSS in the partial subframe.The partial subframe herein corresponds to the first subframe in thisembodiment of the present invention. Obviously, in this case, the userequipment served by the first cell does not need to learn the DMTCconfiguration of the third cell. However, if the data transmissionfeature of the first cell in the first subframe is limited only when thepartial subframe (that is, the first subframe) is located in the DMTC ofthe third cell, the user equipment served by the first cell needs tolearn the DMTC of the third cell, and the first cell and the third cellneed to learn the DMTC configuration of each other through interaction.

The foregoing description is also applicable to another implementationmanner.

In FIG. 10, a last subframe in one burst data transmission (a Data burstin FIG. 10) is the first subframe, and a subframe index number of thelast subframe is 0. Because a time length of the first subframe is lessthan a DRS data transmission length (a DRS data transmission length is12 OFDM symbols), if a PSS and an SSS are sent in an oblique line partin the figure, DRS misinterpreting is caused. Therefore, in thisembodiment, it is limited that a PSS and/or an SSS is not sent in thefirst subframe. In this case, the user terminal detects no PSS and/orSSS, and the user terminal does not incorrectly consider that thesubframe 0 includes a DRS.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, and the first subframe is located in a DMTC of the carrieron which the first cell is located, the data transmission characteristicis that the downlink data transmission length of the first subframe isan element included in a first time set. That is, a preset rule is: Whenthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is located in the DMTC of the carrier onwhich the first cell is located, the downlink data transmission lengthof the first subframe is the element included in the first time set.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, the data transmission characteristic is that the downlinkdata transmission length of the first subframe is an element included ina first time set. That is, a preset rule is: When the first subframe isa first subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, the downlink data transmission length of the first subframeis the element included in the first time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the firsttime set is only: one or more of three OFDM symbols, six OFDM symbols,12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols, and the first timeset does not include another element except the one or more of threeOFDM symbols, six OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13OFDM symbols. For example, if the element included in the first time setis: three OFDM symbols and six OFDM symbols, the first time set includesonly the two elements, and does not include another element. When thedownlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the first time set is:one or more of three OFDM symbols, five OFDM symbols, 10 OFDM symbols,or 12 OFDM symbols, and the first time set does not include anotherelement except the one or more of three OFDM symbols, five OFDM symbols,10 OFDM symbols, or 12 OFDM symbols. For example, if the elementincluded in the first time set is: three OFDM symbols and five OFDMsymbols, the first time set includes only the two elements, and does notinclude another element.

As can be seen from that the element included in the first time setmakes the first cell incapable of sending a PSS and/or an SSS in thefirst subframe, or makes the downlink data transmission length of thefirst cell capable of supporting DRS sending. Therefore, when thedownlink data transmission length of the first subframe is the elementincluded in the first time set, a DRS-based RRM measurement is notaffected, either.

In still another embodiment of the present invention, if the presetcondition is that the first subframe is a first subframe or a sixthsubframe in a radio frame, and the first subframe is located in a DMTCof the carrier on which the first cell is located, the data transmissioncharacteristic is that the downlink data transmission length of thefirst subframe is an element included in a second time set. If thepreset condition is that the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin a DMTC of the carrier on which the first cell is located, the datatransmission characteristic is that the downlink data transmissionlength of the first subframe is an element included in a third time set.The second time set includes at least one element different from that inthe third time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the secondtime set is: one or more of three OFDM symbols, six OFDM symbols, 12OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols, and the elementincluded in the third time set is: one or more of three OFDM symbols,six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11 OFDM symbols,12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols. When the downlinkdata transmission configuration of the first cell is an extended cyclicprefix, the element included in the second time set is: one or more ofthree OFDM symbols, five OFDM symbols, 10 OFDM symbols, or 12 OFDMsymbols, and the element included in the third time set is: one or moreof three OFDM symbols, five OFDM symbols, eight OFDM symbols, nine OFDMsymbols, 10 OFDM symbols, or 12 OFDM symbols.

It should be noted that, if the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin the DMTC of the carrier on which the first cell is located, a datatransmission length of the first subframe may be not limited, that is,the downlink data transmission length of the first subframe may be atime resource occupied by any quantity of OFDM symbols. That is, whenthe downlink data transmission configuration is a normal cyclic prefix,the data transmission length of the first subframe may be any one of 1to 14 OFDM symbols; or when the downlink data transmission configurationis an extended cyclic prefix, the data transmission length of the firstsubframe may be any one of 1 to 12 OFDM symbols. However, in a DwPTS, ina case in which the downlink data transmission configuration is a normalcyclic prefix, a downlink data transmission length of the DwPTS is threeOFDM symbols, six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11OFDM symbols, or 12 OFDM symbols; or when the downlink data transmissionconfiguration is an extended cyclic prefix, a downlink data transmissionlength of the DwPTS is three OFDM symbols, five OFDM symbols, eight OFDMsymbols, nine OFDM symbols, or 10 OFDM symbols. Therefore, when thedownlink data transmission configuration of the first cell is a normalcyclic prefix, the element included in the third time set is: one ormore of three OFDM symbols, six OFDM symbols, nine OFDM symbols, 10 OFDMsymbols, 11 OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13 OFDMsymbols. When the downlink data transmission configuration of the firstcell is an extended cyclic prefix, the element included in the thirdtime set is: one or more of three OFDM symbols, five OFDM symbols, eightOFDM symbols, nine OFDM symbols, 10 OFDM symbols, or 12 OFDM symbols.

As can be seen from that, when the first subframe is not located in theDMTC of the carrier on which the first cell is located, the datatransmission length of the first subframe is not limited. This ensuresdata transmission efficiency, and improves spectrum utilization.

It should be noted that, in an embodiment of the present invention, thepreset rule (or the determining, by the user equipment, a datatransmission characteristic of the cell in the first subframe based on apreset condition) may further include: If the first subframe is a firstsubframe (a subframe 0) or a sixth subframe (a subframe 5) in a radioframe, the downlink data transmission length of the first subframe mayinclude: one or more of three OFDM symbols, six OFDM symbols, 12 OFDMsymbols, 14 OFDM symbols, or 13 OFDM symbols if the downlink datatransmission configuration is a normal cyclic prefix; or one or more ofthree OFDM symbols, five OFDM symbols, 10 OFDM symbols, or 12 OFDMsymbols if the downlink data transmission configuration is an extendedcyclic prefix. In this case, when the downlink data transmissionconfiguration is a normal cyclic prefix, only when the downlink datatransmission length of the first subframe is 12 or 14 OFDM symbols, theuser equipment considers that the first subframe includes a primarysynchronization signal PSS and a secondary synchronization signal SSS,at least four OFDM symbols carry a CRS, a last symbol that carries theCRS is a twelfth OFDM symbol in the first subframe, and the PSS iscarried in the seventh OFDM symbol in the first subframe. When thedownlink data transmission configuration is an extended cyclic prefix,only when the downlink data transmission length of the first subframe is10 or 12 OFDM symbols, the user equipment considers that the subframeincludes a primary synchronization signal PSS and a secondarysynchronization signal SSS, at least four OFDM symbols carry a CRS, alast symbol that carries the CRS is a tenth OFDM symbol in the firstsubframe, and the PS S is carried in the sixth OFDM symbol in the firstsubframe.

It should be noted that, in an embodiment of the present invention, thepreset rule (or the determining, by the user equipment, a datatransmission characteristic of the cell in the first subframe based on apreset condition) may further include: If the first subframe is a firstsubframe (a subframe 0) or a sixth subframe (a subframe 5) in a radioframe, the downlink data transmission length of the first subframe isnot limited. The downlink data transmission length of the first subframemay include: one or more of three OFDM symbols, six OFDM symbols, 12OFDM symbols, 14 OFDM symbols, 13 OFDM symbols, nine OFDM symbols, 10OFDM symbols, or 11 OFDM symbols if the downlink data transmissionconfiguration is a normal cyclic prefix; or one or more of three OFDMsymbols, five OFDM symbols, 10 OFDM symbols, 12 OFDM symbols, eight OFDMsymbols, or nine OFDM symbols if the downlink data transmissionconfiguration is an extended cyclic prefix. In this case, when thedownlink data transmission configuration is a normal cyclic prefix, whenthe downlink data transmission length of the first subframe is nine or10 or 11 OFDM symbols, the first subframe does not include a PSS and/oran SSS, and if there is a PSS, the PSS is carried in the seventh OFDMsymbol in the first subframe; or when the downlink data transmissionconfiguration is an extended cyclic prefix, when the downlink datatransmission length of the first subframe is eight or nine OFDM symbols,the first subframe does not include a PSS and/or an SSS, and if there isa PSS, the PSS is carried in the sixth OFDM symbol in the firstsubframe.

It should be noted that, in an embodiment of the present invention, thepreset rule (or the determining, by the user equipment, a datatransmission characteristic of the cell in the first subframe based on apreset condition) may further include: If the first subframe is locatedin the DMTC of the carrier on which the first cell is located (asubframe index number of the first subframe may be any integer value in0 to 9), when the downlink data transmission configuration is a normalcyclic prefix, only when a length of the first subframe is 12 OFDMsymbols or 14 OFDM symbols, the user equipment assumes that the firstsubframe includes a DRS, and when the length of the first subframe isanother value except the 12 OFDM symbols and the 14 OFDM symbols, theuser equipment does not assume that the first subframe includes a DRS;or when the downlink data transmission configuration is an extendedcyclic prefix, only when a length of the first subframe is 10 OFDMsymbols or 12 OFDM symbols, the user equipment assumes that the firstsubframe includes a DRS, and when the length of the first subframe isanother value except the 10 OFDM symbols and the 12 OFDM symbols, theuser equipment does not assume that the first subframe includes a DRS.

In an embodiment of the present invention, the determining, by the userequipment, a data transmission characteristic of the first cell in thefirst subframe based on a preset condition includes: When a timeresource of a CSI-RS and/or a CSI-IM of the user equipment overlaps thefirst subframe, the first subframe includes the CSI-RS and/or the CSI-IMof the user equipment. The CSI-RS and/or the CSI-IM of the userequipment is periodically configured. However, for user equipment in anLTE system release 12, CSI-RS and CSI-IM transmission is not supportedin a DwPTS. In this embodiment, the CSI-RS and CSI-IM transmission issupported, and a channel state information measurement and a channelstate interference information measurement are implemented.

It should be noted that, in this embodiment of the present invention,the data transmission length of the first subframe may include 14 OFDMsymbols if the first threshold corresponds to a value greater than 1 ms.

It should be noted that, in this embodiment of the present invention, ina radio frame, a first subframe is a subframe whose subframe indexnumber is 0 and a sixth subframe is a subframe whose subframe indexnumber is 5. When the first subframe is the subframe whose subframeindex number is 0, the first slot included in the first subframe is aslot whose slot index number is 0. When the first subframe is thesubframe whose subframe index number is 5, the first slot included inthe first subframe is a slot whose slot index number is 10.

It should be noted that, in this embodiment of the present invention,the first threshold, the preset condition, the data transmissioncharacteristic, the element included in the first time set, the elementincluded in the second time set, and the element included in the thirdtime set may be pre-configured, for example, may be pre-configured basedon a standard protocol specification, or may be set before delivery ofthe access network device and the user equipment, or may be notified byusing higher layer signaling such as radio resource control (RRC)signaling, or may be notified by using physical layer signaling.Specific implementation manners are not limited. If the first subframeis a first subframe (that is, a subframe 0) or a sixth subframe (thatis, a subframe 5) in a radio frame, and the first subframe is located inthe DMTC of the carrier on which the first cell is located, the datatransmission characteristic is that a last OFDM symbol of a first slotincluded in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal.

FIG. 11 is a flowchart of a data sending method based on an embodimentof the present invention.

S111: An access network device detects whether a current channel isidle, and if it is detected, within a period of time, that the channelis idle, continues to perform step 112. Step 111 is an optional step.

Specifically, when a wireless communications system occupies anunlicensed frequency band for communication, a detect before send (LBT)rule needs to be used. Whether a channel has been occupied may bedetected by using a clear channel assessment (CCA).

S112: The access network device determines a downlink data transmissionlength of a first subframe transmitted by a first cell, where thedownlink data transmission length of the first subframe is less than afirst threshold.

Exemplarily, a data transmission start position of the first subframe ison a subframe boundary, and the first subframe is a last subframe in oneburst data transmission, referring to FIG. 6. In FIG. 6, the firstsubframe is a last subframe (a fifth subframe) in one burst datatransmission when the first cell transmits data on a working carrier ofthe first cell.

In an embodiment of the present invention, step 112 further includes:sending, by the access network device, control information, where thecontrol information indicates that the downlink data transmission lengthof the first subframe is less than the first threshold. It should benoted that, in this embodiment of the present invention, the sending, bythe access network device, control information may include: sending, bya cell served by the access network device, the control information. Theaccess network device herein may be a base station, for example, a firstaccess network device in FIG. 4. Sending, by the first access networkdevice, the control information may be understood as sending, by thefirst cell or a second cell, the control information.

In an example, a subframe that carries the control information is anysubframe that is included in the first cell and that is in atransmission burst, referring to FIG. 6; or may be any subframe in thesecond cell. More specifically, the subframe that carries the controlinformation may be any subframe within a time range, corresponding to adata burst of the first cell, of the second cell. The second cell andthe first cell are jointly used through CA or DC. Preferably, a carrieron which the second cell is located and a working frequency range of thesecond cell belong to a frequency resource included in a licensedfrequency band. For the time range, corresponding to the data burst ofthe first cell, of the second cell, refer to FIG. 7. That is, thecontrol information may be sent by using the first cell, or may be sentby using the second cell. That is, the control information may becarried by using time and frequency resources included in a service datachannel of the first cell or time and frequency resources included in acontrol data channel of the first cell, or may be carried by using timeand frequency resources included in a service data channel of the secondcell or time and frequency resources included in a control data channelof the second cell. The control information may be UE specific controlinformation, or may be cell specific control information. Particularly,when the control information is UE specific control information, thecontrol information may be carried in downlink data scheduling signalingfor scheduling the UE.

The control data channel is one or more of control data channelssupported by an LTE system, such as a PDCCH, a PCFICH, a PHICH, anEPDCCH, and a PBCH.

The service data channel is one or more of service data channelssupported by the LTE system, such as a PDSCH and a PMCH.

It should be noted that, in this embodiment of the present invention,the control information indicates that downlink data transmission of thefirst subframe is less than the first threshold. When the firstthreshold is 1 ms, the control information may directly indicate that atarget subframe is the first subframe (or a partial subframe), or maydirectly indicate a data transmission length of a target subframe. Thetarget subframe herein may be any subframe in a data transmission burstof the first cell, for example, any one of afirst/second/third/fourth/fifth subframe in FIG. 6. Alternatively, thetarget subframe may be any subframe on a carrier on which the first cellis located, and in this case, in the target subframe, the first cell maypreempt an unlicensed frequency band resource, or may preempt nounlicensed frequency band resource. When the first threshold is greaterthan 1 ms, the control information may indicate whether the targetsubframe is a subframe in a data transmission burst of the first cell.Explanation of a data transmission burst is the same as above, anddetails are not described.

In another embodiment of the present invention, step 112 furtherincludes: indicating, by the access network device by using a referencesignal including a reference sequence, that the downlink datatransmission length of the first subframe is less than the firstthreshold.

Specifically, the access network device may send the reference signalincluding a reference sequence in any subframe in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold.

Preferably, the access network device adds the reference signalincluding a reference sequence to a third OFDM symbol in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold. Further, the access network device adds a primarysynchronization signal (PSS) to a third OFDM symbol in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold. That is, the access network device adds the PSS to a thirdOFDM symbol in the target subframe, to indicate that the target subframeis the first subframe.

The reference sequence may include but is not limited to the followingsequences: a constant amplitude zero auto correlation (CAZAC) sequence,a binary sequence, an m sequence, a pseudo-random sequence, and a ZCsequence.

In still another embodiment of the present invention, the access networkdevice sends pre-configuration information, and the pre-configurationinformation indicates a longest time within which the first celltransmits data on a carrier on which the first cell is located. Thelongest data transmission time refers to a maximum time range of oneburst data transmission of the first cell on the carrier on which thefirst cell is located. For example, in Japan, for use of an unlicensedfrequency band, it is clearly defined in a regulation that a maximumdata transmission time is 4 ms. In addition, in Europe, for use of anunlicensed frequency band, it is clearly defined in a regulation that amaximum data transmission time is 10 ms or 13 ms or 8 ms. Referring toFIG. 7, FIG. 7 is a schematic diagram of determining a first subframebased on pre-configuration information.

Specifically, the access network device configures, for user equipmentby using higher layer signaling, the pre-configuration informationindicating the longest data transmission time, for example, indicatesthe pre-configuration information to the user equipment by using radioresource control (RRC) signaling.

In an example, when a downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the first threshold is 14 OFDMsymbols or 1 ms (millisecond); and in this case, a complete subframeincludes 14 OFDM symbols, or a time resource occupied by a completesubframe is 1 millisecond (1 ms). When a downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, the firstthreshold is 12 OFDM symbols or 1 ms; and in this case, a completesubframe includes 12 OFDM symbols, or a time resource occupied by acomplete subframe is 1 millisecond (1 ms). Therefore, when the downlinkdata transmission configuration of the first cell is a normal cyclicprefix, and the first threshold is 14 OFDM symbols or 1 ms, or when thedownlink data transmission configuration of the first cell is anextended cyclic prefix, and the first threshold is 12 OFDM symbols or 1ms, the first subframe is an incomplete subframe, that is, a partialsubframe, because the downlink data transmission length of the firstsubframe is less than the first threshold. It should be noted that thefirst threshold may be a value greater than 1 ms; and in this case, thefirst subframe may be a complete subframe, or may be a partial subframe.

S113: The access network device determines a data transmissioncharacteristic of the first subframe in the first cell based on a presetcondition, so that the access network device sends, based on the datatransmission characteristic, data including the first subframe.

In an embodiment of the present invention, if the preset condition isthat the first subframe is a first subframe (that is, a subframe 0) or asixth subframe (that is, a subframe 5) in a radio frame, and the firstsubframe is located in a DMTC of the carrier on which the first cell islocated, the data transmission characteristic is that a last OFDM symbolof a first slot included in the first subframe does not include aprimary synchronization signal and/or a second last OFDM symbol of afirst slot included in the first subframe does not include a secondarysynchronization signal. That is, the determining, by the access networkdevice, a data transmission characteristic of the first subframe in thefirst cell according to a preset condition includes: When the firstsubframe is a first subframe or a sixth subframe in a radio frame, andthe first subframe is located in the DMTC of the carrier on which thefirst cell is located, a last OFDM symbol of a first slot included inthe first subframe does not include a primary synchronization signaland/or a second last OFDM symbol of a first slot included in the firstsubframe does not include a secondary synchronization signal.

In an embodiment of the present invention, if the preset condition isthat the first subframe is a first subframe (that is, a subframe 0) or asixth subframe (that is, a subframe 5) in a radio frame, the datatransmission characteristic is that a last OFDM symbol of a first slotincluded in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. That is, when the first subframe is a firstsubframe or a sixth subframe in a radio frame, and the first subframe islocated in a DMTC of the carrier on which the first cell is located, alast OFDM symbol of a first slot included in the first subframe does notinclude a primary synchronization signal and/or a second last OFDMsymbol of a first slot included in the first subframe does not include asecondary synchronization signal.

As can be seen from that, if the downlink data transmissionconfiguration is a normal cyclic prefix, the last OFDM symbol of thefirst slot refers to a seventh OFDM symbol of the first slot, which isalso a seventh OFDM symbol included in the first subframe, and thesecond last OFDM symbol of the first slot refers to a sixth OFDM symbolof the first slot, which is also a sixth OFDM symbol included in thefirst subframe. If the downlink data transmission configuration is anextended cyclic prefix, the last OFDM symbol of the first slot refers toa sixth OFDM symbol of the first slot, which is also a sixth OFDM symbolincluded in the first subframe, and the second last OFDM symbol of thefirst slot refers to a fifth OFDM symbol of the first slot, which isalso a fifth OFDM symbol included in the first subframe. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

Besides, when the first subframe is a partial subframe, to reducecomplexity, for data transmission of the first subframe, reference maybe made to a data resource mapping manner supported by a downlink pilottimeslot (DwPTS). The DwPTS is a structure in time division duplexing(TDD) and LTE systems, and the DwPTS is included in a special subframe.A frame structure in an existing TDD LTE system includes a downlinksubframe, a special subframe, and an uplink subframe, as shown in FIG.9.

With reference to a quantity of OFDM symbols supported by the DwPTS,when the downlink data transmission configuration is a normal cyclicprefix, the downlink data transmission length of the first subframe isless than 12 OFDM symbols. Further, the downlink data transmissionlength of the first subframe is less than 12 OFDM symbols but greaterthan five OFDM symbols. When the downlink data transmissionconfiguration is an extended cyclic prefix, the downlink datatransmission length of the first subframe is less than 10 OFDM symbols,or the downlink data length of the first subframe is less than 10 OFDMsymbols but greater than four OFDM symbols.

Besides, considering that when the downlink data transmissionconfiguration is a normal cyclic prefix, a DRS includes 12 OFDM symbolsin time, if a data transmission length of the first subframe is lessthan 12 OFDM symbols, the length is not sufficient to support DRSsending. Therefore, a preset rule may be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols, a last OFDM symbol of a firstslot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Moreover, considering that when the datatransmission length of the first subframe is not greater than five OFDMsymbols, the first cell is limited by the data transmission length andtherefore cannot send a PSS or an SSS in the first subframe, when thedata transmission length of the first subframe is not greater than fiveOFDM symbols, a DRS-based RRM measurement is not affected, either.Therefore, the preset rule may further be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols but greater than five OFDMsymbols, a last OFDM symbol of a first slot included in the firstsubframe does not include a primary synchronization signal and/or asecond last OFDM symbol of a first slot included in the first subframedoes not include a secondary synchronization signal. When the downlinkdata transmission configuration is an extended cyclic prefix, the presetrule may further be: When the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is located inthe DMTC of the carrier on which the first cell is located, when andonly when the data transmission length of the first subframe is lessthan 10 OFDM symbols or is less than 10 OFDM symbols but greater thanfour OFDM symbols, a last OFDM symbol of a first slot included in thefirst subframe does not include a primary synchronization signal and/ora second last OFDM symbol of a first slot included in the first subframedoes not include a secondary synchronization signal.

In another embodiment of the present invention, the preset rule mayfurther be: When the first subframe is a first subframe or a sixthsubframe in a radio frame, when and only when the data transmissionlength of the first subframe is less than 12 OFDM symbols or is lessthan 12 OFDM symbols but greater than 5 OFDM symbols, a last OFDM symbolof a first slot included in the first subframe does not include aprimary synchronization signal and/or a second last OFDM symbol of afirst slot included in the first subframe does not include a secondarysynchronization signal. When the downlink data transmissionconfiguration is an extended cyclic prefix, the preset rule may furtherbe: When the first subframe is a first subframe or a sixth subframe in aradio frame, when and only when the data transmission length of thefirst subframe is less than 10 OFDM symbols or is less than 10 OFDMsymbols but greater than four OFDM symbols, a last OFDM symbol of afirst slot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, and the first subframe is located in a DMTC of the carrieron which the first cell is located, the data transmission characteristicis that the downlink data transmission length of the first subframe isan element included in a first time set. That is, a preset rule is: Whenthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is located in the DMTC of the carrier onwhich the first cell is located, the downlink data transmission lengthof the first subframe is the element included in the first time set.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, the data transmission characteristic is that the downlinkdata transmission length of the first subframe is an element included ina first time set. That is, a preset rule is: When the first subframe isa first subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, the downlink data transmission length of the first subframeis the element included in the first time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the firsttime set is only: one or more of three OFDM symbols, six OFDM symbols,12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols, and the first timeset does not include another element except the one or more of threeOFDM symbols, six OFDM symbols, 12 OFDM symbols, 14 OFDM symbols, or 13OFDM symbols. For example, if the element included in the first time setis: three OFDM symbols and six OFDM symbols, the first time set includesonly the two elements, and does not include another element. When thedownlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the first time set is:one or more of three OFDM symbols, five OFDM symbols, 10 OFDM symbols,or 12 OFDM symbols, and the first time set does not include anotherelement except the one or more of three OFDM symbols, five OFDM symbols,10 OFDM symbols, or 12 OFDM symbols. For example, if the elementincluded in the first time set is: three OFDM symbols and five OFDMsymbols, the first time set includes only the two elements, and does notinclude another element.

As can be seen from that the element included in the first time setmakes the first cell incapable of sending a PSS and/or an SSS in thefirst subframe. Therefore, when the downlink data transmission length ofthe first subframe is the element included in the first time set, aDRS-based RRM measurement is not affected, either.

In still another embodiment of the present invention, if the presetcondition is that the first subframe is a first subframe or a sixthsubframe in a radio frame, and the first subframe is located in a DMTCof the carrier on which the first cell is located, the data transmissioncharacteristic is that the downlink data transmission length of thefirst subframe is an element included in a second time set. If thepreset condition is that the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin a DMTC of the carrier on which the first cell is located, the datatransmission characteristic is that the downlink data transmissionlength of the first subframe is an element included in a third time set.The second time set includes at least one element different from that inthe third time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the secondtime set is: one or more of three OFDM symbols, six OFDM symbols, 12OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols, and the elementincluded in the third time set is: one or more of three OFDM symbols,six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11 OFDM symbols,12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols. When the downlinkdata transmission configuration of the first cell is an extended cyclicprefix, the element included in the second time set is: one or more ofthree OFDM symbols, five OFDM symbols, 10 OFDM symbols, or 12 OFDMsymbols, and the element included in the third time set is: one or moreof three OFDM symbols, five OFDM symbols, eight OFDM symbols, nine OFDMsymbols, 10 OFDM symbols, or 12 OFDM symbols.

It should be noted that, if the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin the DMTC of the carrier on which the first cell is located, a datatransmission length of the first subframe may be not limited, that is,the downlink data transmission length of the first subframe may be atime resource occupied by any quantity of OFDM symbols. That is, whenthe downlink data transmission configuration is a normal cyclic prefix,the data transmission length of the first subframe may be any one of 1to 14 OFDM symbols, which is not limited herein; or when the downlinkdata transmission configuration is an extended cyclic prefix, the datatransmission length of the first subframe may be any one of 1 to 12 OFDMsymbols. However, in a DwPTS, in a case in which the downlink datatransmission configuration is a normal cyclic prefix, a downlink datatransmission length of the DwPTS is three OFDM symbols, six OFDMsymbols, nine OFDM symbols, 10 OFDM symbols, 11 OFDM symbols, or 12 OFDMsymbols; or when the downlink data transmission configuration is anextended cyclic prefix, a downlink data transmission length of the DwPTSis three OFDM symbols, five OFDM symbols, eight OFDM symbols, nine OFDMsymbols, or 10 OFDM symbols. Therefore, when the downlink datatransmission configuration of the first cell is a normal cyclic prefix,the element included in the third time set is: one or more of three OFDMsymbols, six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11 OFDMsymbols, 12 OFDM symbols, 14 OFDM symbols, or 13 OFDM symbols; or whenthe downlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the third time set is:one or more of three OFDM symbols, five OFDM symbols, eight OFDMsymbols, nine OFDM symbols, 10 OFDM symbols, or 12 OFDM symbols.

As can be seen from that, when the first subframe is not located in theDMTC of the carrier on which the first cell is located, the datatransmission length of the first subframe is not limited. This ensuresdata transmission efficiency, and improves spectrum utilization.

It should be noted that, in this embodiment of the present invention,the determining, by the access network device, a downlink datatransmission length of a first subframe transmitted by a first cell maybe understood as determining, by the access network device, a downlinkdata transmission length of transmission of the first cell in the firstsubframe. The access network device may determine the downlink datatransmission length of the first subframe based on service load, a timeposition of a resource preempted on an unlicensed frequency band, and amaximum time of one burst data transmission on the unlicensed frequencyband, or may determine the downlink data transmission length of thefirst subframe in another manner, which is not limited herein.

In an embodiment of the present invention, the determining, by theaccess network device, a data transmission characteristic of the firstcell in the first subframe based on a preset condition includes: whenthe first subframe includes a CSI-RS and/or a CSI-IM, sending the firstsubframe including the CSI-RS and/or the CSI-IM. The CSI-RS and/or theCSI-IM is periodically configured.

It should be noted that, in this embodiment of the present invention,the data transmission length of the first subframe may include 14 OFDMsymbols if the first threshold corresponds to a value greater than 1 ms.

It should be noted that, in this embodiment of the present invention,the first threshold, the preset condition, the data transmissioncharacteristic, the element included in the first time set, the elementincluded in the second time set, and the element included in the thirdtime set may be pre-configured, for example, may be pre-configured basedon a standard protocol specification, or may be set before delivery ofthe access network device and the user equipment, or may be notified byusing higher layer signaling such as radio resource control (RRC)signaling, or may be notified by using physical layer signaling.Specific implementation manners are not limited.

FIG. 12 is a schematic diagram of user equipment according to anembodiment of the present invention. The user equipment may be acommunications terminal, for example, a terminal device such as a mobilephone, a tablet computer, a notebook computer, a ultra-mobile personalcomputer (UMPC), a netbook, or a personal digital assistant (PDA), ormay be a relay.

A person skilled in the art may understand that a structure of the userequipment shown in FIG. 12 does not limit the user equipment, and moreor fewer components than those shown in the figure may be included, orsome components may be combined, or a different component deployment maybe used.

In FIG. 12, the user equipment 120 includes a processor 121, a memory122, a receiving unit 123, and a system bus 124. Communication andconnection between the processor 121, the memory 122, and the receivingunit 123 are implemented by using the system bus 124.

The processor 121 may be a general-purpose central processing unit(CPU), a micro processor, an application-specific integrated circuit(ASIC), or one or more integrated circuits, and is configured to executea related program.

The processor 121 is configured to: determine first information of afirst cell, and determine a first subframe based on the firstinformation, where a downlink data transmission length of the firstsubframe is less than a first threshold. The processor 121 is furtherconfigured to determine a data transmission characteristic of the firstcell in the first subframe based on a preset condition.

The memory 122 may be a read only memory (ROM), a static storage device,a dynamic device, or a random access memory (RAM). The memory 122 maystore an operating system and another application program. When thetechnical solutions provided in the embodiments of the present inventionare implemented by using software or firmware, program code used toimplement any optional technical solution provided in the foregoingmethod embodiments of the present invention is stored in the memory 122and executed by the processor 121.

The receiving unit 123 obtains, from a radio channel (for example, aservice data channel or a control data channel), data including thefirst subframe.

The system bus 124 may include a channel, to transfer informationbetween the components of the equipment 120 (for example, the processor121, the memory 122, and the receiving unit 123).

Functions of the processor 121 are described below in detail.

In an example, the processor 121 detects the first information in thefirst cell. Further, the processor 121 detects the first information ona working carrier or carrier frequency of the first cell, where theworking carrier of the first cell belongs to an unlicensed frequencyband. That is, the processor 121 detects the first information on atarget carrier, where the target frequency band is a frequency band onwhich the first cell is located. That the target frequency band is afrequency band on which the first cell is located refers to that thefirst cell may transmit data by using the target frequency band.

For example, if the working carrier frequency of the first cell is F1,the processor 121 detects the first information on a frequency resourcecorresponding to the working carrier frequency F1. The frequencyresource may be represented by a center frequency of the frequencyresource and a size of the frequency resource. The working carrier ofthe first cell (which may also be referred to as a carrier on which thefirst cell is located) may be configured by an access network device(for example, a base station) in the first cell for the user terminal.After the processor 121 obtains the configured working carrier of thefirst cell, the processor 121 detects the first information on thecarrier.

Preferably, the first information carries identity information of thefirst cell. For example, the first information carries a cellidentification (Cell ID) of the first cell, so that the user equipmentcan determine whether the first information detected by the userequipment belongs to the first cell.

It should be noted that the first cell may include a serving cell of theuser equipment, and may further include a neighboring cell of theserving cell of the user equipment (for example, the third cell in FIG.4). The serving cell and the neighboring cell may be located on a samecarrier or different carriers.

In an embodiment of the present invention, the first information iscontrol information, and the processor 121 detects the controlinformation on a control data channel and/or a service data channel ofthe first cell, or the processor 121 detects the control information ona control data channel and/or a service data channel of a second cell,where the first cell is a serving cell of the user equipment, forexample, a secondary cell, and the second cell is also a serving cell ofthe user equipment, for example, a primary cell. A carrier on which thesecond cell is located is different from the carrier on which the firstcell is located. The first cell and the second cell may jointly providea data service to the user equipment through CA or DC. Correspondingly,if the processor 121 detects the control information by using thecontrol data channel and/or the service data channel of the second cell,to determine the first subframe, and the first subframe is a subframe inthe first cell, it may be considered that the second cell indicates thefirst subframe by using a cross-carrier indication. If the processor 121detects the control information by using the control data channel and/orthe service data channel of the first cell, to determine the firstsubframe, it may be considered that the first cell indicates the firstsubframe by using an intra-carrier indication.

The control data channel of the first cell (or the second cell) is oneor more of control data channels supported by an LTE system, such as aphysical downlink control channel (PDCCH), a physical control formatindicator channel (PCFICH), a physical hybrid automatic repeat requestindicator channel (PHICH), an enhanced physical downlink control channel(EPDCCH), and a physical broadcast channel (PBCH).

The service data channel of the first cell (or the second cell) is oneor more of service data channels supported by the LTE system, such as aphysical downlink shared channel (PDSCH) and a physical multicastchannel (PMCH).

In an example, a subframe that carries the control information is anysubframe that is included in the first cell and that is in one burstdata transmission, referring to FIG. 6; or may be any subframe in thesecond cell. More specifically, the burst data transmission may be anysubframe within a time range, corresponding to one burst datatransmission of the first cell, of the second cell. The second cell andthe first cell are jointly used through CA or DC. Preferably, thecarrier on which the second cell is located and a working frequencyrange of the second cell belong to a frequency resource included in alicensed frequency band. For the working frequency range of the secondcell and the time range, corresponding to the burst data transmission ofthe first cell, of the second cell, refer to FIG. 7. That is, thecontrol information may be sent by using the first cell, or may be sentby using the second cell. That is, the control information may becarried by using time and frequency resources included in the servicedata channel of the first cell or time and frequency resources includedin the control data channel of the first cell, or may be carried byusing time and frequency resources included in the service data channelof the second cell or time and frequency resources included in thecontrol data channel of the second cell. The control information may beUE specific control information, or may be cell specific controlinformation. Particularly, when the control information is UE specificcontrol information, the control information may be carried in downlinkdata scheduling signaling for scheduling the UE.

It should be noted that, in this embodiment of the present invention,the control information indicates that downlink data transmission of thefirst subframe is less than the first threshold. When the firstthreshold is 1 ms, the control information directly indicates that atarget subframe is the first subframe (for example, a partial subframe).Alternatively, the control information may directly indicate a datatransmission length of a target subframe, and in this case, theprocessor 121 determines, based on a correspondence between the datatransmission length of the target subframe and the first threshold,whether the target subframe is the first subframe (or the partialsubframe). The target subframe herein may be any subframe in one burstdata transmission of the first cell, for example, any one of afirst/second/third/fourth/fifth subframe in FIG. 6. Alternatively, thetarget subframe may be any subframe on the carrier on which the firstcell is located. When the first threshold is greater than 1 ms, thecontrol information may indicate whether the target subframe is asubframe in one burst data transmission of the first cell. Explanationof one burst data transmission is the same as above, and details are notdescribed.

In another embodiment of the present invention, the first information isa reference signal including a reference sequence.

Specifically, the processor 121 detects, in each subframe included inone burst data transmission of the first cell, whether there is areference signal including a reference sequence, where the first cellmay include a serving cell of the user equipment. Besides, the processor121 may further detect, in each subframe included in a second cell,whether there is a reference signal including a reference sequence, todetermine whether a subframe, corresponding to the subframe, of thefirst cell is the first subframe. Herein, the subframe, corresponding tothe subframe, of the first cell may include a subframe having a samesubframe index number as the subframe, or a subframe having a fixedsubframe offset.

Preferably, the processor 121 performs detection on a third OFDM symbolin each subframe in one burst data transmission of the first cell, todetect whether there is a reference signal including a referencesequence in the third OFDM symbol. Further, the processor 121 detects,in a third OFDM symbol in each subframe included in one burst datatransmission, whether there is a primary synchronization signal (PSS).That is, if the processor 121 detects a PSS in a third OFDM symbol in atarget subframe, the processor 121 may determine that the targetsubframe is the first subframe (or a partial subframe). Otherwise, theprocessor 121 may determine that the target subframe is a completesubframe. The target subframe herein is any subframe in one burst datatransmission. Besides, because a CRS carries the identity information ofthe first cell, the processor 121 may determine, by detecting the CRS,whether the target subframe is the first subframe. That is, after theprocessor 121 detects the CRS, the processor 121 may determine that asubframe including the CRS is the first subframe. In other words, if theCRS is detected, it indicates that the first cell has preempted anunlicensed frequency band resource including the carrier on which thefirst cell is located.

In this embodiment of the present invention, for a method foridentifying, by the processor 121, one burst data transmission of thefirst cell on the carrier on which the first cell is located, a controlinformation detection method or a reference signal detection method maybe used. This is not limited herein. After determining one burst datatransmission, the user equipment may determine the target subframe.

The reference sequence may include but is not limited to the followingsequences: a CAZAC sequence, a binary sequence, an m sequence, apseudo-random sequence, and a ZC sequence.

It should be noted that the reference sequence may correspond todifferent data transmission lengths of the target subframe, whereexplanation of the target subframe is the same as above. That is, inthis embodiment of the present invention, the target subframe mayinclude one subframe in one burst data transmission of the first cell onthe carrier on which the first cell is located, or may be any subframeon the carrier on which the first cell is located.

In still another embodiment of the present invention, the firstinformation is pre-configuration information, and the pre-configurationinformation indicates a longest time within which the first celltransmits data on the carrier on which the first cell is located. Thelongest data transmission time refers to a maximum time range of oneburst data transmission of the first cell on the carrier on which thefirst cell is located. For example, in Japan, for use of an unlicensedfrequency band, it is clearly defined in a regulation that a maximumdata transmission time is 4 ms. In addition, in Europe, for use of anunlicensed frequency band, it is clearly defined in a regulation that amaximum data transmission time is 10 ms or 13 ms or 8 ms. Refer to FIG.8. In FIG. 8, the user equipment may first determine a start position ofone burst data transmission, which may be implemented by detectingcontrol information, detecting a reference sequence, or the like, whichis not specifically limited in this embodiment of the present invention.In FIG. 8, the processor 121 detects a CRS and determines a startposition of one burst data transmission, and then obtains a position ofa partial subframe, that is, a fifth subframe marked in FIG. 8, throughcalculation based on the pre-configuration information, to determine thefirst subframe.

Besides, the pre-configuration information may be a standard protocolspecification, or may be configured for the user terminal by the accessnetwork device in the first cell (for example, an LTE base station) byusing higher layer signaling, for example, indicated to the userterminal by using radio resource control (RRC) signaling.

In an example, when a downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the first threshold is 14 OFDMsymbols or 1 ms (millisecond); and in this case, a complete subframeincludes 14 OFDM symbols, or a time resource occupied by a completesubframe is 1 millisecond (1 ms). When a downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, the firstthreshold is 12 OFDM symbols or 1 ms; and in this case, a completesubframe includes 12 OFDM symbols, or a time resource occupied by acomplete subframe is 1 millisecond (1 ms).

It should be noted that the first threshold may be greater than 1 ms;and in this case, the first subframe may include a complete subframe, ormay include a partial subframe (that is, a subframe whose length indownlink data transmission is less than 1 ms).

In an embodiment of the present invention, the processor 121 determinesthe first subframe based on the control information, and the controlinformation indicates that the downlink data transmission length of thefirst subframe is less than the first threshold. In other words, theprocessor 121 determines the partial subframe based on the controlinformation, which includes determining a time position of the partialsubframe.

Besides, the control information may indicate that a particular subframeis the first subframe (or the partial subframe), where the particularsubframe may be a subframe carrying the control information, or may be asubframe indicated by the control information. The subframe indicated bythe control information may be represented by a subframe index number,or may be represented by a subframe after the subframe including thecontrol information, where a given time interval exists between thesubframe and the subframe including the control information, and thetime interval may be represented by an integer quantity of OFDM symbolsor an integer quantity of slots or an integer quantity of Tss. A Tscorresponds to a reciprocal of a sampling rate used for datatransmission in an LTE system. For example, in the LTE system, a lengthcorresponding to 307200 Tss is one radio frame, that is, 10 ms, and alength corresponding to 15360 Tss is half a subframe (one slot), thatis, 0.5 ms, as shown in FIG. 6.

In FIG. 6, the first subframe is a last subframe in one burst datatransmission (the fifth subframe in FIG. 6) when the first celltransmits data on the working carrier of the first cell (that is, thecarrier on which the first cell is located). The control information maybe carried in the last subframe, to indicate that a current subframe isthe first subframe, or the control information may be carried in anysubframe in one burst data transmission, for example, a second subframe,a third subframe, or a fourth subframe included in the burst datatransmission, to indicate that a last subframe is the first subframe. Itshould be noted that, in FIG. 6, a data transmission length of a firstsubframe included in the burst data transmission is less than 1 ms.Although the first subframe is a partial subframe, the first subframe isnot the first subframe determined based on the first information. Inthis embodiment of the present invention, the first subframe is the lastsubframe in the burst data transmission in FIG. 6, that is, the fifthsubframe in FIG. 6. As can be seen from that a data transmission startposition included in the first subframe is on a subframe boundary. Adata transmission start position included in the first subframe is noton a subframe boundary. Therefore, the first subframe in FIG. 6 is notthe first subframe.

Besides, the subframe carrying the control information may be anysubframe in one burst data transmission of the first cell, or may be anysubframe in the second cell. The second cell is the same as thatdescribed above, and the second cell and the first cell may jointlyprovide a data service to the user equipment through CA or DC or thelike.

In still another embodiment of the present invention, the processor 121determines the first subframe based on the pre-configurationinformation, and the pre-configuration information indicates the longesttime within which the first cell transmits data on the carrier on whichthe first cell is located. The first subframe is a last subframe in thedata transmission, and the processor 121 determines the first subframebased on the pre-configuration information.

Preferably, the user terminal obtains a position of the first subframebased on the pre-configuration information by determining a startposition of one burst data transmission. Specifically, the processor 121determines, through blind cell-specific reference signal (CRS) detectionin each subframe included in the first cell, whether the first cell haspreempted an unlicensed frequency band resource in the currentlydetected subframe. Once the processor detects a CRS, the processordetermines that the first cell has preempted an unlicensed frequencyband resource in the currently detected subframe. In this case, theprocessor 121 uses a position of the currently detected CRS as a startposition of one burst data transmission, and then determines, based onthe pre-configuration information (that is, a configured longest datatransmission time), a position of a last subframe included in the burstdata transmission, to determine the first subframe.

In an embodiment of the present invention, if the preset condition isthat the first subframe is a first subframe (that is, a subframe 0) or asixth subframe (that is, a subframe 5) in a radio frame, and the firstsubframe is located in a discovery signals measurement timingconfiguration (DMTC) of the carrier on which the first cell is located,the data transmission characteristic is that a last OFDM symbol of afirst slot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. That is, a preset rule is: When the firstsubframe is a first subframe or a sixth subframe in a radio frame, andthe first subframe is located in the DMTC of the carrier on which thefirst cell is located, a last OFDM symbol of a first slot included inthe first subframe does not include a primary synchronization signaland/or a second last OFDM symbol of a first slot included in the firstsubframe does not include a secondary synchronization signal.

In this implementation manner, if the first subframe does not include aPSS and/or an SSS, the processor 121 detects no PSS and/or SSS whenexecuting an RRM measurement, and therefore does not incorrectlyconsider that the first subframe includes DRS sending. In this case,even though the first subframe is a partial subframe, the user equipmentdoes not misinterpret the RRM measurement, thereby ensuring accuracy ofthe RRM measurement.

The following describes in detail relationships between a radio frame, asubframe, a slot, and an OFDM symbol. For an LTE system, one radio frameincludes 10 subframes, and each subframe includes two slots. If a datatransmission configuration is a normal cyclic prefix and a subcarrierspacing is 15 KHz, each subframe includes 14 OFDM symbols, and each slotincludes seven OFDM symbols. If a data transmission configuration is anextended cyclic prefix and a subcarrier spacing is 15 KHz, each subframeincludes 12 OFDM symbols, and each slot includes six OFDM symbols. In anLTE system, a radio frame may be represented by a radio frame indexnumber, and the radio frame index number is any integer value in 0 to1023. A subframe may be represented by a position in a radio frame, andthe position in a radio frame may be represented by a subframe index.The subframe index is any integer value in 0 to 9. A subframe whosesubframe index number is M corresponds to an (M+1)^(th) subframe in aradio frame. A slot may also be represented by a position in a radioframe, and the position in a radio frame may be represented by a slotindex. The slot index is any integer value in 0 to 19. A slot whose slotindex number is N corresponds to an (N+1)^(th) slot in a radio frame. AnOFDM symbol may be represented by a position in a subframe, or may berepresented by a position in a slot. The position in a subframe may berepresented by an OFDM symbol index, the OFDM symbol index is an anyinteger value in 0 to 13 or 0 to 11, and an OFDM symbol whose OFDMsymbol index is K corresponds to a (K+1)^(th) OFDM symbol in a subframe.The position in a slot may also be represented by an OFDM symbol index,the OFDM symbol index is any integer value in 0 to 6 or 0 to 5, and anOFDM symbol whose OFDM symbol index is L corresponds to an (L+1)^(th)OFDM symbol in a slot.

As can be seen from that, if the downlink data transmissionconfiguration is a normal cyclic prefix, the last OFDM symbol of thefirst slot refers to a seventh OFDM symbol of the first slot, which isalso a seventh OFDM symbol included in the first subframe, and thesecond last OFDM symbol of the first slot refers to a sixth OFDM symbolof the first slot, which is also a sixth OFDM symbol included in thefirst subframe. If the downlink data transmission configuration is anextended cyclic prefix, the last OFDM symbol of the first slot refers toa sixth OFDM symbol of the first slot, which is also a sixth OFDM symbolincluded in the first subframe, and the second last OFDM symbol of thefirst slot refers to a fifth OFDM symbol of the first slot, which isalso a fifth OFDM symbol included in the first subframe. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

Besides, when the first subframe is a partial subframe, to reducecomplexity, for data transmission of the first subframe, reference maybe made to a data resource mapping manner supported by a downlink pilottimeslot (DwPTS). The DwPTS is a structure in time division duplexing(TDD) and LTE systems, and the DwPTS is included in a special subframe.A frame structure in an existing TDD LTE system includes a downlinksubframe, a special subframe, and an uplink subframe, as shown in FIG.9.

With reference to a quantity of OFDM symbols supported by the DwPTS,when the downlink data transmission configuration is a normal cyclicprefix, the downlink data transmission length of the first subframe isless than 12 OFDM symbols. Further, the downlink data transmissionlength of the first subframe is less than 12 OFDM symbols but greaterthan five OFDM symbols.

When the downlink data transmission configuration is an extended cyclicprefix, the downlink data transmission length of the first subframe isless than 10 OFDM symbols, or the downlink data length of the firstsubframe is less than 10 OFDM symbols but greater than four OFDMsymbols.

Besides, considering that when the downlink data transmissionconfiguration is a normal cyclic prefix, a DRS includes 12 OFDM symbolsin time, if a data transmission length of the first subframe is lessthan 12 OFDM symbols, the length is not sufficient to support DRSsending. Therefore, the preset rule may be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols, a last OFDM symbol of a firstslot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Moreover, considering that when the datatransmission length of the first subframe is not greater than five OFDMsymbols, the first cell is limited by the data transmission length andtherefore cannot send a PSS or an SSS in the first subframe, when thedata transmission length of the first subframe is not greater than fiveOFDM symbols, a DRS-based RRM measurement is not affected, either.Therefore, the preset rule may further be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols but greater than five OFDMsymbols, a last OFDM symbol of a first slot included in the firstsubframe does not include a primary synchronization signal and/or asecond last OFDM symbol of a first slot included in the first subframedoes not include a secondary synchronization signal. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, and the first subframe is located in a DMTC of the carrieron which the first cell is located, the data transmission characteristicis that the downlink data transmission length of the first subframe isan element included in a first time set. That is, a preset rule is: Whenthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is located in the DMTC of the carrier onwhich the first cell is located, the downlink data transmission lengthof the first subframe is the element included in the first time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the firsttime set is only: one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols, and the first time set does not include anotherelement except the one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols. For example, if the element included in the firsttime set is: three OFDM symbols and six OFDM symbols, the first time setincludes only the two elements, and does not include another element.When the downlink data transmission configuration of the first cell isan extended cyclic prefix, the element included in the first time setis: one or more of three OFDM symbols, five OFDM symbols, or 10 OFDMsymbols, and the first time set does not include another element exceptthe one or more of three OFDM symbols, five OFDM symbols, or 10 OFDMsymbols. For example, if the element included in the first time set is:three OFDM symbols and five OFDM symbols, the first time set includesonly the two elements, and does not include another element.

As can be seen from that the element included in the first time setmakes the first cell incapable of sending a PSS and/or an SSS in thefirst subframe. Therefore, when the downlink data transmission length ofthe first subframe is the element included in the first time set, aDRS-based RRM measurement is not affected, either.

In still another embodiment of the present invention, if the presetcondition is that the first subframe is a first subframe or a sixthsubframe in a radio frame, and the first subframe is located in a DMTCof the carrier on which the first cell is located, the data transmissioncharacteristic is that the downlink data transmission length of thefirst subframe is an element included in a second time set. If thepreset condition is that the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin a DMTC of the carrier on which the first cell is located, the datatransmission characteristic is that the downlink data transmissionlength of the first subframe is an element included in a third time set.The second time set includes at least one element different from that inthe third time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the secondtime set is only: one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols, and the element included in the third time set isonly: one or more of three OFDM symbols, six OFDM symbols, nine OFDMsymbols, 10 OFDM symbols, 11 OFDM symbols, or 12 OFDM symbols. When thedownlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the second time set isonly: one or more of three OFDM symbols, five OFDM symbols, 10 OFDMsymbols, and the element included in the third time set is only: one ormore of three OFDM symbols, five OFDM symbols, eight OFDM symbols, nineOFDM symbols, or 10 OFDM symbols.

It should be noted that, if the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin the DMTC of the carrier on which the first cell is located, a datatransmission length of the first subframe may be not limited, that is,the downlink data transmission length of the first subframe may be atime resource occupied by any quantity of OFDM symbols. That is, whenthe downlink data transmission configuration is a normal cyclic prefix,the data transmission length of the first subframe may be any one of 1to 14 OFDM symbols; or when the downlink data transmission configurationis an extended cyclic prefix, the data transmission length of the firstsubframe may be any one of 1 to 12 OFDM symbols. However, in a DwPTS, ina case in which the downlink data transmission configuration is a normalcyclic prefix, a downlink data transmission length of the DwPTS is threeOFDM symbols, six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11OFDM symbols, or 12 OFDM symbols; or when the downlink data transmissionconfiguration is an extended cyclic prefix, a downlink data transmissionlength of the DwPTS is three OFDM symbols, five OFDM symbols, eight OFDMsymbols, nine OFDM symbols, or 10 OFDM symbols. Therefore, when thedownlink data transmission configuration of the first cell is a normalcyclic prefix, the element included in the third time set is only: oneor more of three OFDM symbols, six OFDM symbols, nine OFDM symbols, 10OFDM symbols, 11 OFDM symbols, or 12 OFDM symbols, and does not includeanother quantity of OFDM symbols; or when the downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, theelement included in the third time set is only: one or more of threeOFDM symbols, five OFDM symbols, eight OFDM symbols, nine OFDM symbols,or 10 OFDM symbols, and does not include another quantity of OFDMsymbols.

As can be seen from that, when the first subframe is not located in theDMTC of the carrier on which the first cell is located, the datatransmission length of the first subframe is not limited. This ensuresdata transmission efficiency, and improves spectrum utilization.

In an embodiment of the present invention, the determining, by theprocessor, a data transmission characteristic of the first cell in thefirst subframe based on a preset condition includes: When a timeresource of a CSI-RS and/or a CSI-IM of the user equipment overlaps thefirst subframe, the first subframe includes the CSI-RS and/or the CSI-IMof the user equipment. The CSI-RS and/or the CSI-IM of the userequipment is periodically configured. However, for user equipment in anLTE system release 12, CSI-RS and CSI-IM transmission is not supportedin a DwPTS. In this embodiment, the CSI-RS and CSI-IM transmission issupported, and a channel state information measurement and a channelstate interference information measurement are implemented.

It should be noted that, in this embodiment of the present invention,the data transmission length of the first subframe may include 14 OFDMsymbols if the first threshold corresponds to a value greater than 1 ms.

It should be noted that, in this embodiment of the present invention,the first threshold, the preset condition, the data transmissioncharacteristic, the element included in the first time set, the elementincluded in the second time set, and the element included in the thirdtime set may be pre-configured, for example, may be pre-configured basedon a standard protocol specification, or may be set before delivery ofthe access network device and the user equipment, or may be notified byusing higher layer signaling such as radio resource control (RRC)signaling, or may be notified by using physical layer signaling.Specific implementation manners are not limited.

A data receiving method according to an embodiment of the presentinvention is described above. A person skilled in the art is aware thatthe method embodiment and the steps and processes may be implemented byhardware. A person skilled in the art may construct correspondingmodules and make variations according to the foregoing methodembodiment, and these modules and variations shall fall within theprotection scope of the present invention. Details are not describedherein.

FIG. 13 is a schematic diagram of an access network device according toan embodiment of the present invention. The access network device is,for example, an LTE base station.

A person skilled in the art may understand that a structure of theaccess network device shown in FIG. 13 does not limit the access networkdevice, and more or fewer components than those shown in the figure maybe included, or some components may be combined, or a differentcomponent deployment may be used.

In FIG. 13, the access network device 130 includes a determining unit131, a sending unit 132, and a system bus 133. Communication andconnection between the determining unit 131 and the sending unit 132 areimplemented by using the system bus 133.

The determining unit 131 is configured to determine a downlink datatransmission length of a first subframe transmitted by a first cell,where the downlink data transmission length of the first subframe isless than a first threshold; and configured to determine a datatransmission feature of the first cell in the first subframe based on apreset condition. The sending unit 132 sends, to the first cell in apublic address manner, downlink transmission data including the firstsubframe.

The system bus 133 may include a channel, to transfer informationbetween the components of the device 130 (for example, the determiningunit 131 and the sending unit 132).

Functions of the determining unit 131 are described below in detail.

In an example, a data transmission start position of the first subframeis on a subframe boundary, and the first subframe is a last subframe inone burst data transmission, as shown in FIG. 6. In FIG. 6, the firstsubframe is a last subframe in one burst data transmission (a fifthsubframe) when the first cell transmits data on a working carrier of thefirst cell.

In an embodiment of the present invention, the sending unit 132 sendscontrol information, and the control information indicates that thedownlink data transmission length of the first subframe is less than thefirst threshold. It should be noted that, in this embodiment of thepresent invention, the sending, by the sending unit 132, controlinformation may include: sending, by a cell served by the access networkdevice, the control information. The access network device herein may bea base station. For example, sending, by a sending unit in a firstaccess network device in FIG. 4, the control information may beunderstood as sending, by the first cell or a second cell, the controlinformation.

In an example, a subframe that carries the control information is anysubframe that is included in the first cell and that is in atransmission burst, referring to FIG. 6; or may be any subframe in thesecond cell. More specifically, the subframe that carries the controlinformation may be any subframe within a time range, corresponding to adata burst of the first cell, of the second cell. The second cell andthe first cell are jointly used through CA or DC. Preferably, a carrieron which the second cell is located and a working frequency range of thesecond cell belong to a frequency resource included in a licensedfrequency band. For the time range, corresponding to the data burst ofthe first cell, of the second cell, refer to FIG. 7. That is, thecontrol information may be sent by using the first cell, or may be sentby using the second cell. That is, the control information may becarried by using time and frequency resources included in a service datachannel of the first cell or time and frequency resources included in acontrol data channel of the first cell, or may be carried by using timeand frequency resources included in a service data channel of the secondcell or time and frequency resources included in a control data channelof the second cell. The control information may be user equipmentspecific control information, or may be cell specific controlinformation. Particularly, when the control information is userequipment specific control information, the control information may becarried in downlink data scheduling signaling for scheduling the userequipment.

The control data channel is one or more of control data channelssupported by an LTE system, such as a PDCCH, a PCFICH, a PHICH, anEPDCCH, and a PBCH.

The service data channel is one or more of service data channelssupported by the LTE system, such as a PDSCH and a PMCH.

It should be noted that, in this embodiment of the present invention,the control information indicates that downlink data transmission of thefirst subframe is less than the first threshold. When the firstthreshold is 1 ms, the control information may directly indicate that atarget subframe is the first subframe (or a partial subframe), or maydirectly indicate a data transmission length of a target subframe. Thetarget subframe herein may be any subframe in a data transmission burstof the first cell, for example, any one of afirst/second/third/fourth/fifth subframe in FIG. 6. Alternatively, thetarget subframe may be any subframe on a carrier on which the first cellis located, and in this case, in the target subframe, the first cell maypreempt an unlicensed frequency band resource, or may preempt nounlicensed frequency band resource. When the first threshold is greaterthan 1 ms, the control information may indicate whether the targetsubframe is a subframe in a data transmission burst of the first cell.Explanation of a data transmission burst is the same as above, anddetails are not described.

In another embodiment of the present invention, the sending unit 132sends a reference signal including a reference sequence, and thereference signal including a reference sequence indicates that thedownlink data transmission length of the first subframe is less than thefirst threshold.

Specifically, the sending unit 132 may send the reference signalincluding a reference sequence in any subframe in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold.

Preferably, the determining unit 131 adds the reference signal includinga reference sequence to a third OFDM symbol in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold. Further, the determining unit 131 adds a primarysynchronization signal (PSS) to a third OFDM symbol in one burst datatransmission including the first subframe, to indicate that the downlinkdata transmission length of the first subframe is less than the firstthreshold. That is, the determining unit 131 adds the PSS to a thirdOFDM symbol in the target subframe, to indicate that the target subframeis the first subframe.

The reference sequence may include but is not limited to the followingsequences: a CAZAC sequence, a binary sequence, an m sequence, apseudo-random sequence, and a ZC sequence.

In still another embodiment of the present invention, the sending unit132 is further configured to send pre-configuration information, and thepre-configuration information indicates a longest time within which thefirst cell transmits data on a carrier on which the first cell islocated. The longest data transmission time refers to a maximum timerange of one burst data transmission of the first cell on the carrier onwhich the first cell is located. For example, in Japan, for use of anunlicensed frequency band, it is clearly defined in a regulation that amaximum data transmission time is 4 ms. In addition, in Europe, for useof an unlicensed frequency band, it is clearly defined in a regulationthat a maximum data transmission time is 10 ms or 13 ms or 8 ms.Referring to FIG. 7, FIG. 7 is a schematic diagram of determining afirst subframe based on pre-configuration information.

Specifically, the determining unit 131 configures, for user equipment byusing higher layer signaling, the pre-configuration informationindicating the longest data transmission time, for example, indicatesthe pre-configuration information to the user equipment by using radioresource control (RRC) signaling.

In an example, when a downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the first threshold is 14 OFDMsymbols or 1 ms (millisecond); and in this case, a complete subframeincludes 14 OFDM symbols, or a time resource occupied by a completesubframe is 1 millisecond (1 ms). When a downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, the firstthreshold is 12 OFDM symbols or 1 ms; and in this case, a completesubframe includes 12 OFDM symbols, or a time resource occupied by acomplete subframe is 1 millisecond (1 ms). Therefore, when the downlinkdata transmission configuration of the first cell is a normal cyclicprefix, and the first threshold is 14 OFDM symbols or 1 ms, or when thedownlink data transmission configuration of the first cell is anextended cyclic prefix, and the first threshold is 12 OFDM symbols or 1ms, the first subframe is an incomplete subframe, that is, a partialsubframe, because the downlink data transmission length of the firstsubframe is less than the first threshold.

In an embodiment of the present invention, if the preset condition isthat the first subframe is a first subframe (that is, a subframe 0) or asixth subframe (that is, a subframe 5) in a radio frame, and the firstsubframe is located in a DMTC of the carrier on which the first cell islocated, the data transmission characteristic is that a last OFDM symbolof a first slot included in the first subframe does not include aprimary synchronization signal and/or a second last OFDM symbol of afirst slot included in the first subframe does not include a secondarysynchronization signal. That is, when the first subframe is a firstsubframe or a sixth subframe in a radio frame, and the first subframe islocated in the DMTC of the carrier on which the first cell is located, alast OFDM symbol of a first slot included in the first subframe does notinclude a primary synchronization signal and/or a second last OFDMsymbol of a first slot included in the first subframe does not include asecondary synchronization signal.

As can be seen from that, if the downlink data transmissionconfiguration is a normal cyclic prefix, the last OFDM symbol of thefirst slot refers to a seventh OFDM symbol of the first slot, which isalso a seventh OFDM symbol included in the first subframe, and thesecond last OFDM symbol of the first slot refers to a sixth OFDM symbolof the first slot, which is also a sixth OFDM symbol included in thefirst subframe. If the downlink data transmission configuration is anextended cyclic prefix, the last OFDM symbol of the first slot refers toa sixth OFDM symbol of the first slot, which is also a sixth OFDM symbolincluded in the first subframe, and the second last OFDM symbol of thefirst slot refers to a fifth OFDM symbol of the first slot, which isalso a fifth OFDM symbol included in the first subframe. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

Besides, when the first subframe is a partial subframe, to reducecomplexity, for data transmission of the first subframe, reference maybe made to a data resource mapping manner supported by a downlink pilottimeslot (DwPTS). The DwPTS is a structure in time division duplexing(TDD) and LTE systems, and the DwPTS is included in a special subframe.A frame structure in an existing TDD LTE system includes a downlinksubframe, a special subframe, and an uplink subframe, as shown in FIG.9.

With reference to a quantity of OFDM symbols supported by the DwPTS,when the downlink data transmission configuration is a normal cyclicprefix, the downlink data transmission length of the first subframe isless than 12 OFDM symbols. Further, the downlink data transmissionlength of the first subframe is less than 12 OFDM symbols but greaterthan five OFDM symbols. When the downlink data transmissionconfiguration is an extended cyclic prefix, the downlink datatransmission length of the first subframe is less than 10 OFDM symbols,or the downlink data length of the first subframe is less than 10 OFDMsymbols but greater than four OFDM symbols.

Besides, considering that when the downlink data transmissionconfiguration is a normal cyclic prefix, a DRS includes 12 OFDM symbolsin time, if a data transmission length of the first subframe is lessthan 12 OFDM symbols, the length is not sufficient to support DRSsending. Therefore, a preset rule may be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols, a last OFDM symbol of a firstslot included in the first subframe does not include a primarysynchronization signal and/or a second last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal. Moreover, considering that when the datatransmission length of the first subframe is not greater than five OFDMsymbols, the first cell is limited by the data transmission length andtherefore cannot send a PSS or an SSS in the first subframe, when thedata transmission length of the first subframe is not greater than fiveOFDM symbols, a DRS-based RRM measurement is not affected, either.Therefore, the preset rule may further be: When the first subframe is afirst subframe or a sixth subframe in a radio frame, and the firstsubframe is located in the DMTC of the carrier on which the first cellis located, when and only when the data transmission length of the firstsubframe is less than 12 OFDM symbols but greater than five OFDMsymbols, a last OFDM symbol of a first slot included in the firstsubframe does not include a primary synchronization signal and/or asecond last OFDM symbol of a first slot included in the first subframedoes not include a secondary synchronization signal. A process ofanalysis for a case in which the downlink data transmissionconfiguration is an extended cyclic prefix is the same as above, anddetails are not described herein.

In another embodiment of the present invention, if the preset conditionis that the first subframe is a first subframe or a sixth subframe in aradio frame, and the first subframe is located in a DMTC of the carrieron which the first cell is located, the data transmission characteristicis that the downlink data transmission length of the first subframe isan element included in a first time set. That is, a preset rule is: Whenthe first subframe is a first subframe or a sixth subframe in a radioframe, and the first subframe is located in the DMTC of the carrier onwhich the first cell is located, the downlink data transmission lengthof the first subframe is the element included in the first time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the firsttime set is only: one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols, and the first time set does not include anotherelement except the one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols. For example, if the element included in the firsttime set is: three OFDM symbols and six OFDM symbols, the first time setincludes only the two elements, and does not include another element.When the downlink data transmission configuration of the first cell isan extended cyclic prefix, the element included in the first time setis: one or more of three OFDM symbols, five OFDM symbols, or 10 OFDMsymbols, and the first time set does not include another element exceptthe one or more of three OFDM symbols, five OFDM symbols, or 10 OFDMsymbols. For example, if the element included in the first time set is:three OFDM symbols and five OFDM symbols, the first time set includesonly the two elements, and does not include another element.

As can be seen from that the element included in the first time setmakes the first cell incapable of sending a PSS and/or an SSS in thefirst subframe. Therefore, when the downlink data transmission length ofthe first subframe is the element included in the first time set, aDRS-based RRM measurement is not affected, either.

In still another embodiment of the present invention, if the presetcondition is that the first subframe is a first subframe or a sixthsubframe in a radio frame, and the first subframe is located in a DMTCof the carrier on which the first cell is located, the data transmissioncharacteristic is that the downlink data transmission length of thefirst subframe is an element included in a second time set. If thepreset condition is that the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin a DMTC of the carrier on which the first cell is located, the datatransmission characteristic is that the downlink data transmissionlength of the first subframe is an element included in a third time set.The second time set includes at least one element different from that inthe third time set.

In an example, when the downlink data transmission configuration of thefirst cell is a normal cyclic prefix, the element included in the secondtime set is only: one or more of three OFDM symbols, six OFDM symbols,or 12 OFDM symbols, and the element included in the third time set isonly: one or more of three OFDM symbols, six OFDM symbols, nine OFDMsymbols, 10 OFDM symbols, 11 OFDM symbols, or 12 OFDM symbols. When thedownlink data transmission configuration of the first cell is anextended cyclic prefix, the element included in the second time set isonly: one or more of three OFDM symbols, five OFDM symbols, 10 OFDMsymbols, and the element included in the third time set is only: one ormore of three OFDM symbols, five OFDM symbols, eight OFDM symbols, nineOFDM symbols, or 10 OFDM symbols.

It should be noted that, if the first subframe is a first subframe or asixth subframe in a radio frame, and the first subframe is not locatedin the DMTC of the carrier on which the first cell is located, a datatransmission length of the first subframe may be not limited, that is,the downlink data transmission length of the first subframe may be atime resource occupied by any quantity of OFDM symbols. That is, whenthe downlink data transmission configuration is a normal cyclic prefix,the data transmission length of the first subframe may be any one of 1to 14 OFDM symbols; or when the downlink data transmission configurationis an extended cyclic prefix, the data transmission length of the firstsubframe may be any one of 1 to 12 OFDM symbols. However, in a DwPTS, ina case in which the downlink data transmission configuration is a normalcyclic prefix, a downlink data transmission length of the DwPTS is threeOFDM symbols, six OFDM symbols, nine OFDM symbols, 10 OFDM symbols, 11OFDM symbols, or 12 OFDM symbols; or when the downlink data transmissionconfiguration is an extended cyclic prefix, a downlink data transmissionlength of the DwPTS is three OFDM symbols, five OFDM symbols, eight OFDMsymbols, nine OFDM symbols, or 10 OFDM symbols. Therefore, when thedownlink data transmission configuration of the first cell is a normalcyclic prefix, the element included in the third time set is only: oneor more of three OFDM symbols, six OFDM symbols, nine OFDM symbols, 10OFDM symbols, 11 OFDM symbols, or 12 OFDM symbols, and does not includeanother quantity of OFDM symbols; or when the downlink data transmissionconfiguration of the first cell is an extended cyclic prefix, theelement included in the third time set is only: one or more of threeOFDM symbols, five OFDM symbols, eight OFDM symbols, nine OFDM symbols,or 10 OFDM symbols, and does not include another quantity of OFDMsymbols.

As can be seen from that, when the first subframe is not located in theDMTC of the carrier on which the first cell is located, the datatransmission length of the first subframe is not limited. This ensuresdata transmission efficiency, and improves spectrum utilization.

It should be noted that, in this embodiment of the present invention,the determining, by the determining unit 131, a downlink datatransmission length of a first subframe transmitted by a first cell maybe understood as determining, by the determining unit 131, a downlinkdata transmission length of transmission of the first cell in the firstsubframe. The determining unit 131 may determine the downlink datatransmission length of the first subframe based on service load, a timeposition of a resource preempted on an unlicensed frequency band, and amaximum time of one burst data transmission on the unlicensed frequencyband, or may determine the downlink data transmission length of thefirst subframe in another manner, which is not limited herein.

In an embodiment of the present invention, the determining, by thedetermining unit 131, a data transmission characteristic of the firstcell in the first subframe based on a preset condition includes: whenthe first subframe includes a CSI-RS and/or a CSI-IM, sending the firstsubframe including the CSI-RS and/or the CSI-IM. The CSI-RS and/or theCSI-IM is periodically configured.

It should be noted that, in this embodiment of the present invention,the data transmission length of the first subframe may include 14 OFDMsymbols if the first threshold corresponds to a value greater than 1 ms.

It should be noted that, in this embodiment of the present invention,the first threshold, the preset condition, the data transmissioncharacteristic, the element included in the first time set, the elementincluded in the second time set, and the element included in the thirdtime set may be pre-configured, for example, may be pre-configured basedon a standard protocol specification, or may be set before delivery ofthe access network device and the user equipment, or may be notified byusing higher layer signaling such as radio resource control (RRC)signaling, or may be notified by using physical layer signaling.Specific implementation manners are not limited.

A data sending method according to an embodiment of the presentinvention is described above. A person skilled in the art is aware thatthe method embodiment and the steps and processes may be implemented byhardware. A person skilled in the art may construct correspondingmodules and make variations according to the foregoing methodembodiment, and these modules and variations shall fall within theprotection scope of the present invention. Details are not describedherein.

A person skilled in the art may be further aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware, computer software, or a combination thereof. Toclearly describe the interchangeability between the hardware and thesoftware, the foregoing has generally described compositions and stepsof each example based on functions. Whether the functions are performedby hardware or software depends on particular applications and designconstraint conditions of the technical solutions. A person skilled inthe art may use different methods to implement the described functionsfor each particular application, but it should not be considered thatthe implementation goes beyond the scope of the present invention.

Steps of methods or algorithms described in the embodiments disclosed inthis specification may be implemented by hardware, a software moduleexecuted by a processor, or a combination thereof. The software modulemay reside in a random access memory (RAM), a memory, a read-only memory(ROM), an electrically programmable ROM, an electrically erasableprogrammable ROM, a register, a hard disk, a removable disk, a CD-ROM,or any other form of storage medium known in the art.

In the foregoing specific implementation manners, the objectives,technical solutions, and benefits of the present invention are furtherdescribed in detail. It should be understood that the foregoingdescriptions are merely specific implementation manners of the presentinvention, but are not intended to limit the protection scope of thepresent invention. Any modification, equivalent replacement, orimprovement made without departing from the spirit and principle of thepresent invention should fall within the protection scope of the presentinvention.

What is claimed is:
 1. A data receiving method, comprising: determining,by a user equipment, control information of a first cell; determining,by the user equipment, a first subframe in the first cell based on thecontrol information, wherein a downlink data transmission length of thefirst subframe is less than a first threshold; and when the firstsubframe is a first subframe in a radio frame or a sixth subframe in aradio frame, a downlink data transmission configuration of the firstcell is a normal cyclic prefix, and the downlink data transmissionlength of the first subframe is less than 12 orthogonalfrequency-division multiplexing (OFDM) symbols, determining, by the userequipment, that a last OFDM symbol of a first slot included in the firstsubframe does not include a primary synchronization signal and a secondto last OFDM symbol of a first slot included in the first subframe doesnot include a secondary synchronization signal.
 2. The method accordingto claim 1, wherein the determining, by the user equipment, the controlinformation of a first cell comprises: detecting, by the user equipment,the control information on at least one of a control data channel or aservice data channel of the first cell.
 3. The method according to claim1, wherein the first threshold is a value greater than or equal to 1millisecond (ms).
 4. The method according to claim 1, wherein a datatransmission start position of the first subframe is on a subframeboundary, and the first subframe is a last subframe in one burst datatransmission.
 5. A data sending method, comprising: determining, by anaccess network device, a downlink data transmission length of a firstsubframe transmitted by a first cell, wherein the downlink datatransmission length of the first subframe is less than a firstthreshold; when the first subframe is a first subframe in a radio frameor a sixth subframe in a radio frame, a downlink data transmissionconfiguration of the first cell is a normal cyclic prefix, and thedownlink data transmission length of the first subframe is less than 12orthogonal frequency-division multiplexing (OFDM) symbols, determining,by the access network device, that a last OFDM symbol of a first slotincluded in the first subframe does not include a primarysynchronization signal and a second to last OFDM symbol of a first slotincluded in the first subframe does not include a secondarysynchronization signal.
 6. The method according to claim 5, furthercomprising: sending, by the access network device, control information,wherein the control information indicates that the downlink datatransmission length of the first subframe is less than the firstthreshold.
 7. The method according to claim 5, wherein the firstthreshold is a value not less than 1 millisecond (ms).
 8. The methodaccording to claim 5, wherein a data transmission start position of thefirst subframe is on a subframe boundary, and the first subframe is alast subframe in a transmission burst.
 9. A user equipment comprising:at least one processor; and a non-transitory computer-readable storagemedium coupled to the at least one processor and storing programminginstructions for execution by the processor, the programminginstructions instruct the at least one processor to: determine controlinformation of a first cell; determine a first subframe in the firstcell based on the control information, wherein a downlink datatransmission length of the first subframe is less than a firstthreshold; and when the first subframe is a first subframe in a radioframe or a sixth subframe in a radio frame, a downlink data transmissionconfiguration of the first cell is a normal cyclic prefix, and thedownlink data transmission length of the first subframe is less than 12orthogonal frequency-division multiplexing (OFDM) symbols, determinethat a last OFDM symbol of a first slot included in the first subframedoes not include a primary synchronization signal and a second to lastOFDM symbol of a first slot included in the first subframe does notinclude a secondary synchronization signal.
 10. The user equipmentaccording to claim 9, wherein the control information is used toindicate that the downlink data transmission length of the firstsubframe is less than the first threshold.
 11. The user equipmentaccording to claim 9, wherein the first threshold is a value greaterthan or equal to 1 millisecond (ms).
 12. The user equipment according toclaim 9, wherein a data transmission start position of the firstsubframe is on a subframe boundary, and the first subframe is a lastsubframe in a transmission burst.
 13. An access network device, theaccess network device comprising: at least one processor; and anon-transitory computer-readable storage medium coupled to the at leastone processor and storing programming instructions for execution by theprocessor, the programming instructions instruct the at least oneprocessor to: determine a downlink data transmission length of a firstsubframe transmitted by a first cell, wherein the downlink datatransmission length of the first subframe is less than a firstthreshold; when the first subframe is a first subframe in a radio frameor a sixth subframe in a radio frame, a downlink data transmissionconfiguration of the first cell is a normal cyclic prefix, and thedownlink data transmission length of the first subframe is less than 12orthogonal frequency-division multiplexing (OFDM) symbols, determinethat a last OFDM symbol of a first slot included in the first subframedoes not include a primary synchronization signal and a second to lastOFDM symbol of a first slot included in the first subframe does notinclude a secondary synchronization signal.
 14. The access networkdevice according to claim 13, wherein the access network device furthercomprises a transmitter, wherein the transmitter is configured to sendcontrol information, wherein the control information indicates that thedownlink data transmission length of the first subframe is less than thefirst threshold.
 15. The access network device according to claim 13,wherein the first threshold is a value greater than or equal to 1millisecond (ms).
 16. The access network device according to claim 13,wherein a data transmission start position of the first subframe is on asubframe boundary, and the first subframe is a last subframe in atransmission burst.